irq assignments for this motherboard

How to Configure Interrupt Request (IRQ) Priorities in Windows

A real improvement or a placebo tweak?

Most components directly attached to your motherboard—including PCI slots, IDE controllers, serial ports, the keyboard port, and even your motherboard’s CMOS—have individual interrupt requests (IRQs) assigned to them.

An interrupt request line, or IRQ, is a numbered hardware line over which a device can interrupt the normal flow of data to the processor, allowing the device to function.

Windows Vista and 7 lets you prioritize one or more IRQs (which translate to one or more hardware devices), potentially improving the performance of those devices.  Below are basic registry editing tips that you can use to set IRQ priorities.

1. Start by opening the System Information utility (msinfo32.exe), and navigating to System Summary\Hardware Resources\IRQs to view the IRQs in use on your system, and the devices using them.

Take note of IRQ13 (Numeric Data processor) that we will use in this example:

Some users have gotten good results prioritizing IRQ 8 (for the system CMOS) and the IRQ corresponding to the video card, but the feedback is unconfirmed. Do you think it is a placebo tweak? Post your comments!

Founder of Help Desk Geek and managing editor. He began blogging in 2007 and quit his job in 2010 to blog full-time. He has over 15 years of industry experience in IT and holds several technical certifications. Read Aseem's Full Bio

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IRQ Settings, how to view IRQ assignments and resolve IRQ conflicts.

Default isa irq assignments.

Viewing your current IRQ assignments

Opening the list of irqs.

Changing IRQ Settings

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Understanding the IRQ assignments table for my new ASUS A7..

• Thread starter Guest
• Start date Aug 4, 2004
• Tags DDR3 PNY Product Silverline
• Motherboards
• Aug 4, 2004

Archived from groups: alt.comp.periphs.mainboard.asus ( More info? ) I've been building my own systems for about five years now but one thing has always left me guessing as to exactly what information is being conveyed by the tables that appear in every MB manual I've seen regarding the expansion slots and which ones share IRQs. Here is the table from the MB manual and it seems to do nothing but confuse me so I am here hoping someone can explain exactly what this information means: INT A INT B INT C INT D ---------------------------------------------------------------------------- ------ PCI slot 1 --- --- --- used PCI slot 2 red --- --- --- PCI slot 3 --- sed --- --- PCI slot 4 --- --- hared --- PCI slot 5 red --- --- --- Gigabit LAN --- --- hared --- AGP slot (8x) --- --- --- OK here's the thing, every other time I've seen these tables they have had all the columns filled in. So my questions are: How does INT A, INT B, INT C, and INT D relate to the IRQ asigned to a device in a particular slot. And what do they mean by "used" (I hope this does not mean I can't install a card into PCI slots 1 and 3). And finally, how do I determine which of these are *really* "shared" slots (I sure hope the AGP isn't shared with slots 2 and 5). And one final question: How do I determine if a certain device driver supports IRQ sharing? I want to configure this system with Windows-XP PRO and the following add-on cards: (1) ASUS V9180 Magic GeForce MX 440 8X AGP (for primary display) (2) Visiontek GeForce4 MX420 PCI (for second display) (3) ATI TV Wonder Value Edition PCI (TV-Tuner and Video Capture) (4) 3Com/US Robotics 56Kbps VOICE/FAX modem PCI (FAX & digital answering machine) (5) ADI AD1888 SoundMAX 6-channel audio with S/PDIF-out interface (onboard) (6) Marvell 88E8001 Gigabit LAN adapter (onboard) ----- You may send e-mail if you wish provided it is NOT SPAM. To decode my valid E-mail address, you will need to remove the <NOSPAM.> and the <666>. I had to get complicated as spammers are now doing the obvious removal of the word "NOSPAM" to compile their lists of e-mails... - G.L. Cross  

Archived from groups: alt.comp.periphs.mainboard.asus ( More info? ) In article <[email protected]>, "G.L. Cross" <[email protected]> wrote: > I've been building my own systems for about five years now but one > thing has always left me guessing as to exactly what information > is being conveyed by the tables that appear in every MB manual I've > seen regarding the expansion slots and which ones share IRQs. Here > is the table from the MB manual and it seems to do nothing but > confuse me so I am here hoping someone can explain exactly what > this information means: > > INT A INT B INT C > INT D > ------------------------------------------------------------------- > ------ > PCI slot 1 --- --- --- > used > PCI slot 2 > red --- --- --- > PCI slot 3 --- > sed --- --- > PCI slot 4 --- --- > hared --- > PCI slot 5 > red --- --- --- > Gigabit LAN --- --- > hared --- > AGP slot (8x) > --- --- --- > > OK here's the thing, every other time I've seen these tables they > have had all the columns filled in. So my questions are: How does > INT A, INT B, INT C, and INT D relate to the IRQ asigned to a device > in a particular slot. And what do they mean by "used" (I hope this > does not mean I can't install a card into PCI slots 1 and 3). And > finally, how do I determine which of these are *really* "shared" > slots (I sure hope the AGP isn't shared with slots 2 and 5). And > one final question: How do I determine if a certain device driver > supports IRQ sharing? > > I want to configure this system with Windows-XP PRO and the > following add-on cards: > > (1) ASUS V9180 Magic GeForce MX 440 8X AGP (for primary display) > (2) Visiontek GeForce4 MX420 PCI (for second display) > (3) ATI TV Wonder Value Edition PCI (TV-Tuner and Video Capture) > (4) 3Com/US Robotics 56Kbps VOICE/FAX modem PCI (FAX & digital > answering machine) > > (5) ADI AD1888 SoundMAX 6-channel audio with S/PDIF-out interface > (onboard) > (6) Marvell 88E8001 Gigabit LAN adapter (onboard) > > ----- > You may send e-mail if you wish provided it is NOT SPAM. To decode > my valid E-mail address, you will need to remove the <NOSPAM.> and > the <666>. I had to get complicated as spammers are now doing the > obvious removal of the word "NOSPAM" to compile their lists of > e-mails... > > - G.L. Cross INT A INT B INT C INT D PCI slot 1 ‹ ‹ ‹ used PCI slot 2 shared ‹ ‹ ‹ PCI slot 3 ‹ used ‹ ‹ PCI slot 4 ‹ ‹ shared ‹ PCI slot 5 shared ‹ ‹ ‹ Gigabit LAN ‹ ‹ shared ‹ AGP slot shared ‹ ‹ ‹ > How does INT A, INT B, INT C, and INT D relate to the IRQ asigned > to a device in a particular slot. I have a sneaking suspicion that this table only represents about 1/4 of all the wiring information on the motherboard. One of the chipset chips has an interrupt controller on it, and the mislabelled four columns above represent the path the four wires take. Now, the thing is, a PCI card has four interrupt signals on it. A primary and three non-primary signals. From the PCI 2.2. spec: INTA# Interrupt A is used to request an interrupt. INTB# Interrupt B is used to request an interrupt and only has meaning on a multi-function device. << and so on for INTC# and INTD# >> What I think the Asus table is showing above, is how only the INTA# pin on each slot, is connected to the four wires streaming from the interrupt controller. So, in fact, the Asus table doesn't show how a multi-function device would be sharing interrupts. The normal practice in the PCI world is to "swizzle" the connections. This is a regular diagonal connection pattern, intended to equalize the interconnect. It is something like this. (Note: Example truncated to fit onto one line each.) S1 INTA# --> S2 INTB# --> S3 INTC# --> S4 INTD# --> S5 INTA# --> PIRQA# S1 INTB# --> S2 INTC# --> S3 INTD# --> S4 INTA# --> S5 INTB# --> PIRQB# S1 INTC# --> S2 INTD# --> S3 INTA# --> s4 INTB# --> S5 INTC# --> PIRQC# S1 INTD# --> S2 INTA# --> S3 INTB# --> S4 INTC# --> S5 INTD# --> PIRQD# The Asus table is basically only communicating what is happening to INTA# on each card (the primary interrupt). In my swizzle example above, slot1 and slot5 share a physical interrupt line, namely PIRQA#. Asus would mark slot1 and slot5 as "sharing" that signal. Since the PIRQB# signal only has Slot4's INTA# connected to it, Asus would use the word "used" when they should be using the word "unique" or "unshared" instead. To see the swizzle pattern for yourself, see pg.22 of this schematic, and notice how the signals change in an orderly fashion for the INTx#'s http://www.intel.com/design/chipsets/designex/BXDPDG10.PDF > And what do they mean by "used" (I hope this > does not mean I can't install a card into PCI slots 1 and 3). Translate "used" to "unshared" or "unique". Slot 1 or slot 3 is an excellent location for a Sound Card with a poorly written interrupt handler, on your A7V880. > And finally, how do I determine which of these are *really* "shared" > slots (I sure hope the AGP isn't shared with slots 2 and 5). But the AGP _is_ sharing with slot 2 and slot 5. When physical signals are shared, the numeric IRQ assigned by the OS has to be the same for all the devices sharing that signal. Each handler executes sequentially until the PIRQ signal is found to be deasserted - at least that is my understanding of how sharing works. ------------------ Example from Abxzone - P4C800 Deluxe (3C940 Lan on original deluxe) http://abxzone.com/forums/showthread.php?t=48495 A B C D E F G H PCI slot 1 ‹ ‹ ‹ ‹ ‹ shared ‹ ‹ PCI slot 2 ‹ ‹ ‹ ‹ ‹ ‹ shared ‹ PCI slot 3 ‹ ‹ ‹ ‹ ‹ ‹ ‹ shared PCI slot 4 ‹ ‹ ‹ ‹ shared ‹ ‹ ‹ PCI slot 5 ‹ ‹ ‹ ‹ ‹ shared ‹ ‹ AGP Pro shared used ‹ ‹ ‹ ‹ ‹ ‹ USB HC0 shared ‹ ‹ ‹ ‹ ‹ ‹ ‹ USB HC1 ‹ ‹ ‹ used ‹ ‹ ‹ ‹ USB HC2 ‹ ‹ used ‹ ‹ ‹ ‹ ‹ USB HC3 shared ‹ ‹ ‹ ‹ ‹ ‹ ‹ USB 2.0 ‹ ‹ ‹ ‹ ‹ ‹ ‹ shared LAN ‹ ‹ ‹ ‹ ‹ ‹ shared ‹ SATA ‹ ‹ ‹ ‹ ‹ ‹ ‹ shared 1394 ‹ ‹ ‹ ‹ shared ‹ ‹ ‹ "Using the onboard LAN. Using USB. Disabled the firewire. Disabled on-board sound. Firewire card in PCI-3. Audigy1 in Slot #4. I have the Radeon on the AGP." I think his Audigy is actually in Slot 2. Firewire in Slot 3. Resulting Windows IRQ assignment - OCRed to table below: http://abxzone.com/forums/attachment.php?attachmentid=4677 Resource Device status IRQ 0 System timer OK IRQ 1 Standard 101/102-Key or Microsoft Natural PS/2 Keyboard OK IRQ 3 Communications Port (COM2) OK IRQ 4 Communications Port (COMl) OK IRQ 6 Standard floppy disk controller OK IRQ 8 System CMOS/real time clock OK IRQ 9 Microsoft ACPI-Compliant System OK IRQ 10 Intel(R) 82801EB SMBus Controller - 24D3 OK IRQ 12 Microsoft PS/2 Mouse OK IRQ 13 Numeric data processor OK IRQ 14 Primary IDE Channel OK IRQ 15 Secondary IDE Channel OK IRQ 16 RADEON 9700 PRO OK IRQ 16 Standard Universal PCI to USB Host Controller OK IRQ 16 Standard Universal PCI to USB Host Controller OK IRQ 18 Standard Universal PCI to USB Host Controller OK IRQ 19 Standard Universal PCI to USB Host Controller OK IRQ 21 Promise Technology Inc. Ultra IDE Controller OK IRQ 22 3Com Gigabit LOM (3C940) OK IRQ 22 Creative SB Audigy OK IRQ 23 Standard Enhanced PCI to USB Host Controller OK IRQ 23 OHCI Compliant IEEE 1394 Host Controller OK IRQ 23 Texas Instruments OHCI Compliant IEEE 1394 Controller OK Things to note: 1) The Promise controller on IRQ 21, suggest the Asus table is wrong and the Promise is actually on wire "F". 2) IRQ 22 occurs twice, and must match, because 3C940 and Audigy are sharing via Slot 2. 3) IRQ 23 shows two Firewire devices and a USB2. Notice again how the Asus table is wrong. Maybe the SATA and onboard Firewire should be switched in the Asus table ? 4) Standard assignments are IRQ0-IRQ15. PCI devices start above those. IRQ16 to 19 seem to correspond to wires A thru D. IRQ20 to 23 seem to correspond to wires E thru H. The five PCI slots can only use IRQ20 to 23. Notice that the P4C800 Deluxe interrupt controller has eight wires, and yours has four wires. It doesn't change the fact that both boards use sharing. Moral of the story ? Load up the system with hardware first, then look in the Device Manager or use a utility like Sandra, to examine the IRQ assignments. Mark up the manual to reflect the real wiring. Reassign cards, according to your knowledge of cards known not to play nice. In my readings on the newsgroup so far, only a sound card really needs a private IRQ. > one final question: How do I determine if a certain device driver > supports IRQ sharing? Devices with high data thruput, or real time requirements, may have data overruns, data underruns, cause havoc via delays or freezes etc. If your system is misbehaving, start looking... No hardware manufacturer is going to admit they have a problem. Sharing is a requirement, after all, and they cannot admit to such a shortcoming. > I want to configure this system with Windows-XP PRO and the > following add-on cards: > > (1) ASUS V9180 Magic GeForce MX 440 8X AGP (for primary display) > (2) Visiontek GeForce4 MX420 PCI (for second display) > (3) ATI TV Wonder Value Edition PCI (TV-Tuner and Video Capture) > (4) 3Com/US Robotics 56Kbps VOICE/FAX modem PCI (FAX & digital > answering machine) INT A INT B INT C INT D PCI slot 1 ‹ ‹ ‹ used PCI slot 2 shared ‹ ‹ ‹ PCI slot 3 ‹ used ‹ ‹ PCI slot 4 ‹ ‹ shared ‹ PCI slot 5 shared ‹ ‹ ‹ Gigabit LAN ‹ ‹ shared ‹ AGP slot shared ‹ ‹ ‹ You are using onboard sound, so no worry about finding a unique signal for a sound card. Modem card probably has a data pump (non-Winmodem), so will be interrupting when a FIFO of data bytes is ready. TV Tuner might be pumping a fair amount of data on the PCI bus, but doesn't have a good reason to be using its interrupt line. Here are my choices: AGP MX440 AGP (low power card - cooling not an issue) Slot1 MX420 PCI (higher priority than other PCI slots) Slot2 Slot3 USR modem card (unique IRQ, no sharing, low latency) Slot4 ATI TV Wonder Tuner PCI Slot5 I don't really know if the TV Wonder uses interrupts. Once slot1 and slot3 are assigned, the other slots kinda stink. Sharing with the AGP card doesn't sound like fun. Sharing with the LAN would be bad practice as well, only because the interrupt rate on the LAN could be high. I placed the card in slot4, on the assumption that with the modem, you might not be using the LAN. If you are using the LAN, do a file transfer from another PC, with the TV Tuner running or not running, and see if there is a performance difference. Performance tuning will help you decide on a final placement. If the MX440 runs hotter than I think it does, then try swapping the USR modem card and the MX420. If the USR card is smaller than the MX420, maybe it will leave more room for air movement. When I refer to cooling issue, I mean if there is a FX5900 or an ATI 9800 in the AGP slot, you might not want a PCI card in slot 1. I don't know what I'd do if that was the case. Also, if you want a real laugh, download a few more Asus manuals. For example, the PC-DL is a desktop server board, and uses an 875 Northbridge, like the P4C800 Deluxe example above. Look how the tech writer did the table: INTA# INTB# INTC# INTD# PCI slot 1 IRQ_F# IRQ_G# IRQ_H# IRQ_F# PCI slot 2 IRQ_G# IRQ_H# IRQ_E# IRQ_F# PCI slot 3 IRQ_G# IRQ_E# IRQ_F# IRQ_F# PCI slot 4 IRQ_E# IRQ_F# IRQ_G# IRQ_F# PCI slot 5 IRQ_F# IRQ_G# IRQ_H# IRQ_F# AGP Pro IRQ_A# IRQ_B# ‹ ‹ Onboard USB1 IRQ_A# ‹ ‹ ‹ Onboard USB2 IRQ_D# ‹ ‹ ‹ Onboard USB3 IRQ_C# ‹ ‹ ‹ Onboard USB4 IRQ_A# ‹ ‹ ‹ Onboard USB2.0 IRQ_H# ‹ ‹ ‹ Onboard LAN IRQ_F# ‹ ‹ ‹ Onboard 20378R IRQ_H# ‹ ‹ ‹ Onboard IDE IRQ_C# Onboard ICH5R IRQ_C# ‹ ‹ ‹ Onboard 1394 IRQ_E# ‹ ‹ ‹ Onboard AD1985 IRQ_B# Notice how in this example, the table attempts to show all the wiring. You have to rearrange the info from the first column, to make a table similar to the ones found in other Asus desktop motherboard manuals. Also note, how even the AC97 Codec is shown to have an interrupt, although other manuals never show this. The swizzle pattern for the PCI slots, is, in a word, nuts. Every manual I read, just creates more mysteries. HTH, Paul  

Archived from groups: alt.comp.periphs.mainboard.asus ( More info? ) "Stephan Grossklass" <[email protected]> wrote in message news:[email protected]... > [garbled table deleted] > I preferred to d/l the PDF manual... And please, check your line breaks. It was fine when it went out but I noticed the post when it showed up and sent a cancel request for the first one. I guess you didn't notice the repost I put out 46 minutes later... Is there some reason why I should leave the "automatically wrap text at" setting to 76 characters? That's what happened to me the first time (those true-type fonts) and it garbled the table... > It appears PCI slots 1 and 3 do not share an INT line with anything > else, so you should put interrupt sharing unfriendly cards into these. > Slot 4 shares an INT line with the Gb LAN (I wouldn't put anything > bandwidth intensive into that one), while 2 and 5 share one with the AGP > card. Here's the thing that never got explained to me: this table implies that each slot has four "INT lines" but I don't get the relationship between what this means (hardware design-wise) and how these INT A, INT B, INT C, etc. relate in any way to the sharing of IRQs. Plus the use of the word "used" I've never run across before... > > final question: How do I determine if a certain device driver supports IRQ > > sharing? > > You try out. Frequently it's not only a matter of the device itself, the > drivers also play an important role - there have been cases where a card > absolutely despises interrupt sharing in Windows but miraculously worked > fine in Linux. > > > I want to configure this system with Windows-XP PRO and the following > > add-on cards: > > > > (1) ASUS V9180 Magic GeForce MX 440 8X AGP (for primary display) > > Nvidia chips are usually not very keen on interrupt sharing. This fact I am already aware of. Also they sometimes get unstable (at least some of the older ones) if you enable the "Read Around Write" BIOS setting of the VIA chipset. I do not know if this issue has been resolved with the newer Nvidia chips or not. All that aside, Nvidia makes some damn good video chips (the GeForce MX 440 is capable of real-time full-screen antialiasing at a quality I've never seen before and a 200Hz refresh rate at 1024x768 resolution in 32-bit color). > > > (2) Visiontek GeForce4 MX420 PCI (for second display) > > (3) ATI TV Wonder Value Edition PCI (TV-Tuner and Video Capture) > > Put that one into one of the non-shared slots. Same goes for the 2nd > graphics card, I suppose. > > > (4) 3Com/US Robotics 56Kbps VOICE/FAX modem PCI (FAX & digital answering > > machine) > > This can probably live happily next to the Gb LAN. Yes, this is how I was planning to arrange them: AGP ===> ASUS video card PCI-1 ===> Visiontek video card PCI-2 ===> Two additional USB ports cabled to MB header (PCI-2 unused) PCI-3 ===> ATI TV-Tuner / video capture card PCI-4 ===> 56Kbps voice/fax modem PCI-5 ===> (unused) > It would probably be easier to get a Yahoo! mail account, where you can > set up disposable trash addresses. You may want to choose one containing > "nospam"... Funny! I did that once already. After returning from a two-week vacation, I had over 800 SPAM messages, the vast majority of them porno...  

Archived from groups: alt.comp.periphs.mainboard.asus ( More info? ) "Paul" <[email protected]> wrote in message news:[email protected]... > > Now, the thing is, a PCI card has four interrupt signals on it. A > primary and three non-primary signals. > > From the PCI 2.2. spec: > > INTA# Interrupt A is used to request an interrupt. > INTB# Interrupt B is used to request an interrupt and only > has meaning on a multi-function device. > << and so on for INTC# and INTD# >> > > What I think the Asus table is showing above, is how only the INTA# > pin on each slot, is connected to the four wires streaming from the > interrupt controller. So, in fact, the Asus table doesn't show how > a multi-function device would be sharing interrupts. Thanks! I "think" I see what is going on now though I'll have to look over what you are saying some more. > Translate "used" to "unshared" or "unique". Slot 1 or slot 3 is an > excellent location for a Sound Card with a poorly written interrupt > handler, on your A7V880. I am planning on using the onboard 6-channel sound. Seems to me that disabling it and then adding a different sound card - seems kind of "wasteful" since nowadays most onboard sound setups sound just fine to me (unless you are going to be a musician and need MIDI capability and lots of simultaneous "voices" to compose complex music... (just a thought). > Resulting Windows IRQ assignment - OCRed to table below: > http://abxzone.com/forums/attachment.php?attachmentid=4677 > > Resource Device status > IRQ 0 System timer OK > IRQ 1 Standard 101/102-Key or Microsoft Natural PS/2 Keyboard OK > IRQ 3 Communications Port (COM2) OK > IRQ 4 Communications Port (COMl) OK > IRQ 6 Standard floppy disk controller OK > IRQ 8 System CMOS/real time clock OK > IRQ 9 Microsoft ACPI-Compliant System OK > IRQ 10 Intel(R) 82801EB SMBus Controller - 24D3 OK > IRQ 12 Microsoft PS/2 Mouse OK > IRQ 13 Numeric data processor OK > IRQ 14 Primary IDE Channel OK > IRQ 15 Secondary IDE Channel OK > IRQ 16 RADEON 9700 PRO OK > IRQ 16 Standard Universal PCI to USB Host Controller OK > IRQ 16 Standard Universal PCI to USB Host Controller OK > IRQ 18 Standard Universal PCI to USB Host Controller OK > IRQ 19 Standard Universal PCI to USB Host Controller OK > IRQ 21 Promise Technology Inc. Ultra IDE Controller OK > IRQ 22 3Com Gigabit LOM (3C940) OK > IRQ 22 Creative SB Audigy OK > IRQ 23 Standard Enhanced PCI to USB Host Controller OK > IRQ 23 OHCI Compliant IEEE 1394 Host Controller OK > IRQ 23 Texas Instruments OHCI Compliant IEEE 1394 Controller OK Interesting... I've always thought the IRQs stopped at #15. When did this change take place? I've always thought they needed to extend the number of available IRQs but I couldn't think of how it could be done with all the "legacy" stuff out there. > Moral of the story ? Load up the system with hardware first, then > look in the Device Manager or use a utility like Sandra, to examine > the IRQ assignments. Mark up the manual to reflect the real wiring. > Reassign cards, according to your knowledge of cards known not to > play nice. In my readings on the newsgroup so far, only a sound > card really needs a private IRQ. Would it not degrade performance if one or more high-data rate devices (like the two video cards) shared an IRQ? > You are using onboard sound, so no worry about finding a unique > signal for a sound card. Modem card probably has a data pump > (non-Winmodem), so will be interrupting when a FIFO of data bytes > is ready. TV Tuner might be pumping a fair amount of data on the > PCI bus, but doesn't have a good reason to be using its interrupt > line. Here are my choices: > > AGP MX440 AGP (low power card - cooling not an issue) > Slot1 MX420 PCI (higher priority than other PCI slots) > Slot2 > Slot3 USR modem card (unique IRQ, no sharing, low latency) > Slot4 ATI TV Wonder Tuner PCI > Slot5 I will be using the onboard LAN connected to a Microsoft 802.11g/Wi-Fi Wireless-G router to share my cable modem connection with two "wired" systems (mine and my roommate's) and also allow me to wirelessly connect to the Internet from my Hp Pavilion 7000 series notebook. The FAX/VOICE modem is there primarily to send and receive FAX'es which comes in useful a lot. So with that in mind, I'd think about swapping the locations for the modem and the TV Tuner / Video Capture card (one of the reasons I'm putting together a two-display system: full screen TV on one monitor while I work at the other). Also the extra screen realestate can sure come in handy when you've got say a dozen open windows at once. > Also, if you want a real laugh, download a few more Asus manuals. > For example, the PC-DL is a desktop server board, and uses an 875 > Northbridge, like the P4C800 Deluxe example above. Look how the > tech writer did the table: [table omitted] > Every manual I read, just creates more mysteries. I know what you mean. I was quite disappointed with the quality of the manual for this MB. It certainly was not up to ASUS or ABit's usual standards.  

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How to Use IRQ and I/O Addresses to Resolve Conflicts on Windows 10

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Ensuring seamless functionality and optimal performance on your Windows 10 PC can sometimes be challenging, especially when conflicts between your hardware devices pop up—resulting in erratic behavior and system instability.

One of the key factors that affect device conflicts is the interplay of IRQ and I/O addresses. Consequently, grasping the fundamentals of IRQ and I/O addresses and learning how to manage them is vital. By so doing, you can understand how to diagnose and resolve conflicts on your Windows 10 PC.

What Are IRQ and I/O Addresses?

IRQ (Interrupt Request) and I/O (Input/Output) addresses are essential components of a computer's hardware configuration that facilitate communication between devices.

IRQ is a unique number assigned to each hardware device that allows the operating system to manage and prioritize its interactions. Think of it as a digital hand raise that alerts the CPU when a device needs attention. Each device is allocated a specific IRQ, ensuring that requests are processed in the correct order and preventing conflicts.

On the other hand, I/O addresses are pathways for data transfer between devices and the CPU. These addresses define specific regions in the computer's memory where devices can send and receive data. Unique I/O addresses ensure that devices avoid interference and transfer data efficiently.

IRQ and I/O addresses are instrumental in allocating system resources effectively. This prevents clashes for resources like memory or processor time, enabling devices to function seamlessly and efficiently. It also prevents performance bottlenecks, maximizing your PC’s resource utilization.

One of the key benefits of understanding IRQ and I/O addresses is their role in conflict resolution. For example, you can reassign IRQs or modify I/O addresses to ensure that devices work synchronously. This also allows you to optimize data flow between the CPU and these devices.

How to Identify Device Conflicts Related to IRQ and I/O Addresses

To effectively identify device conflicts related to IRQ and I/O addresses, open the Device Manager , which provides a comprehensive overview of all the hardware devices installed on your computer.

Once it’s open, expand the different device categories to view all hardware devices connected to your PC. Look for devices with a yellow triangle icon or an exclamation mark next to them. These symbols indicate potential conflicts or issues with the devices.

To examine the properties of a specific device, right-click on it and select Properties from the context menu. This will open a window displaying detailed information about the device.

Within the device's properties window, navigate to the Resources tab. This tab provides valuable information about the device's IRQ and I/O addresses, which are crucial for identifying conflicts.

Take a closer look at the list of resources the device uses and pay attention to any conflicts related to IRQ and I/O addresses. Conflicts may appear as overlapping or shared resources between multiple devices.

If you encounter a device conflict, it's important that you resolve it to ensure the proper functioning of your hardware components. Here’s how to go about it.

How to Resolve Conflicts by Modifying IRQ and I/O Addresses

To address conflicts related to IRQ and I/O addresses on your Windows 10 system, you can modify the settings of the conflicting devices.

Start by opening the Device Manager and locate devices with a yellow triangle icon or exclamation mark that are experiencing conflicts. Right-click on it and select Properties from the context menu, and in the properties window, navigate to the Resources tab.

Within this tab, you have the option to manually modify the IRQ or I/O address settings to resolve conflicts. Uncheck the Use automatic settings option and look for buttons or options that allow you to change or modify the settings.

Adjust the IRQ or I/O address settings by selecting the specific resource settings from the list and choosing the Change Settings option. It's important to select an available and unused IRQ or I/O address for the device. This will help you avoid choosing resources that are already in use by other devices to prevent further conflicts.

After making the necessary modifications, click OK to save the changes and close the Properties window. Then, restart your computer to allow your operating system recognize and implement the modified IRQ and I/O address configurations.

Once your computer restarts, reopen the Device Manager and check for any remaining conflicts. Ensure the devices no longer display yellow triangle icons or exclamation marks, indicating successful conflict resolution.

Note that modifying IRQ and I/O addresses can potentially impact system stability. You should only make changes if you are experiencing conflicts with the current settings. That way, you can avoid inducing device conflicts yourself. Luckily, you can always revert to the original settings if the modifications do not resolve the issues.

Maximize Your PC's Performance and Overcoming Hardware Conflicts

By understanding and effectively handling IRQ and I/O addresses, you can minimize risks and make the most out of modifying them to address conflicts on your Windows 10 PC.

Although IRQ and I/O addresses are essential for maintaining a well-functioning PC, it doesn’t stop there. You should also explore further options like advanced troubleshooting techniques and optimizing device configurations to maximize your PC’s performance and overcome hardware conflicts.

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interrupt request (IRQ)

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What is an interrupt request (IRQ)?

An interrupt request (IRQ) is a signal sent to a computer's processor to momentarily stop (interrupt) its operations. The signal is usually sent by a hardware device to interrupt the processor so the device gets some time to run its own operation. For example, when a printer finishes printing, it sends an interrupt signal to the computer. This signal momentarily interrupts its central processing unit (CPU) so it can decide what processing to do next.

An IRQ is important when multiple devices are connected to a computer. These devices need time to run their own operations and process some data and must, therefore, ask the processor to stop. They do this with an IRQ.

Once the device sends the IRQ, the processor momentarily stops so the computer can give the device time to run its operation. Every time a user moves a mouse , an interrupt handler tells the processor that it needs to stop what it's currently doing so it can handle and interpret the mouse movements.

IRQ channels and IRQ numbers

All devices connected to the computer communicate their IRQs over a unique data line called a channel . These include disk drive controllers , sound cards , printers , keyboards and mouses. Whenever the IRQ is referenced, it happens alongside the channel number, which is also known as an IRQ number . Each device is assigned its own IRQ number. For example, IRQ 1 may be used for a printer, IRQ 4 for a keyboard and IRQ 7 for a mouse.

Devices require a unique IRQ number to provide inputs to the processor or start a particular action. This number facilitates appropriate CPU response by assigning priorities to the various devices. The lower the IRQ number, the more important the need for the input or action. the system timer is typically assigned an IRQ of 0, while a PS/2 port -- keyboard or mouse -- may have an IRQ of 1. These low numbers prioritize the system timer and PS/2 port over, say, Integrated Drive Electronics primary or IDE secondary ports, which may have high IRQs, like IRQ 14 and IRQ 15, respectively.

IRQ assignments

Usually, IRQs can go up to IRQ 15. Here are typical IRQ assignments for a PC.

IRQ and plug and play

A computer can receive multiple signals on the same interrupt line but may not understand all these signals. To facilitate understanding, a unique value must be specified to the computer for each device and its path. When Industry Standard Architecture devices were in use and before plug-and-play ( PnP ) devices emerged, users had to set IRQ values manually when connecting a new device to a computer. Today, most devices are PnP. So, they are configured automatically, and users don't have to worry about them.

If a user adds a device that does not support PnP, the manufacturer should have provided explicit directions on how to assign IRQ values for it. If they don't know what IRQ value to specify, they'll save time by asking the manufacturer instead of trying to figure it out themselves.

IRQ errors can sometimes occur when installing new hardware or changing the settings of existing hardware (reconfiguration). Conflicts usually occur when two devices or pieces of hardware try to use the same IRQ channel for their IRQs. It is possible for multiple devices to use the same channel, but this is usually not done in practice. So, when simultaneous IRQs come in over the same channel, it results in a conflict.

One example of an IRQ error is IRQL_NOT_LESS_OR_EQUAL. This memory -related error occurs if a system process or a device driver tries to access a memory address but lacks valid access rights to do so. Thus, NOT_LESS_OR_EQUAL, sometimes known simply as IRQL, refers to an attempt to access an address that's outside a set boundary value (upper bound address). This IRQ error may occur due to corrupt system files, incompatible device drivers , faulty hardware or incomplete software installation.

When an IRQL error occurs, an operating system stop is triggered, which causes the OS to crash. If the OS is Windows , the crash triggers a blue screen of death . This is when Windows displays a stop screen with a message like the following: "Your PC ran into a problem and needs to restart. We're just collecting some error info, and then we'll restart for you." The user sees the stop screen as long as Windows is collecting the error data in the background. Once the collection phase ends, the computer reboots by default.

Usually, when an IRQ error occurs, the computer freezes up or devices may stop working. Such errors are a rarity now with PnP devices since there is no need to set IRQ channels manually. That makes it unlikely more than one device tries to use the same IRQ channel and cause a conflict.

How to view and change IRQ settings

In Windows, IRQ settings are usually visible under Device Manager. Changing the View menu option to Resources by type shows the IRQ section. Users can also use System Information. Execute the msinfo32.exe command from the Run dialog box, and navigate to Hardware Resources > IRQs.

To change IRQ settings, go into the BIOS or open Device Manager. To change IRQ settings with Device Manager, do the following:

• Double-click a device to open its Properties window.
• In the Resources tab, deselect the Use automatic settings option.
• Select the hardware configuration that should be changed from the Settings based on drop-down menu.
• Select IRQ from the Resource settings area of the properties.
• Edit the IRQ value from the Change Setting button.

Before changing settings, remember that, if users make errors, their computer may not function correctly. Always note the existing settings before changing anything to be able restore them if something goes wrong.

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IRQ Assignments

Anyone who has ever tried to install a legacy (non plug-and-play) device has learned that device configuration can be a world of confusion for the novice. Fortunately, the entire concept of device configuration can be simplified through the understanding of a few basic terms and concepts.

When discussing device configuration, we typically hear about three basic types of hardware resources: Interrupt Request (IRQ) Line Assignments, Direct Memory Access (DMA) Assignments, and memory locations known as Input/Output (I/O) Addresses. In this series of three articles, I will discuss each of these terms with the intent of clarifying device configuration and resource conflict resolution. This discussion is based upon and applies primarily to current-design IBM-compatible systems operating under Microsoft Windows 98, although the other 32-bit versions of Windows are similar.

Device resource conflicts occur whenever two or more hardware devices attempt to utilize the same resource. Normally, a conflict will simply stop one or more of the involved devices from operating properly. Often, this will be nothing more than an inconvenient nuisance. Sometimes however, the result is far more serious, to the point of not allowing Windows to load properly. A solid understanding of device resources and their assignments can assist the user in avoiding resource conflicts.

Interrupt Request (IRQ) Line Assignments

The Interrupt Request Lines, also known as hardware interrupts, are dedicated signal lines or circuits between the system CPU and hardware devices. These signal lines are used for the purpose of notifying the CPU that the assigned device needs processor attention and vice versa. The simplest way to understand IRQ's is to consider the IRQ as a doorbell when a device requires CPU attention, it places a signal on its assigned IRQ line. The CPU senses this signal and responds by stopping it's current operation and shifting its attention to the "interrupting" device.

In this modern era of high-speed computers, we like to think that our PC's are whizzes at doing multiple jobs simultaneously. Hold on to your hats for the reality of it, folks - for all practical purposes, even the fastest CPU in a PC today is only capable of doing one thing at a time! It only seems like the CPU is doing multiple jobs, due to the fact that the CPU is capable of switching between tasks tens of thousands of times every second. To mere mortals, the apparent effect is that of a CPU doing all kinds of things at the same time. OK, so what does any of this have to do with IRQ's? As a kind of answer, ask yourself a question - "What happens when I try to talk to someone who is too busy to listen?" The IRQ's are the chosen method of making the (too busy) CPU listen to the other devices in the PC. When the CPU receives an IRQ signal, it must stop what it is doing and devote its attention to the interrupting device. These hardware interrupts are known as maskable interrupts, meaning that the processor can temporarily mask or ignore the interrupt request long enough to complete its current task. There is also a Non-Maskable Interrupt or NMI - an interrupt that cannot be ignored even temporarily - but we're not going to worry about that for this discussion, as it is in no way user-configurable.

Let's look at a basic rundown of what is behind the whole hardware interrupt scheme. Consider the system keyboard. The keyboard controller on a typical system is a fairly limited device, with no real storage capability (memory) to speak of, and the CPU is responsible for moving the keystroke to the keyboard buffer. Each time the user presses a key, the generated keystroke signal must be passed off to the CPU immediately, because the next incoming keystroke will replace or overwrite the previous one if that one hasn't been stored yet. So what would happen to the incoming keystrokes if the CPU is busy doing something else and so is unable to handle them? The obvious answer is that they would be lost. To prevent this from occurring, the engineers have given the keyboard system the ability to demand processor attention. The keyboard controller, immediately upon receipt of an incoming keystroke, activates its assigned hardware interrupt line (IRQ1). The Intel 8259A IRQ controller chip accepts this interrupt request and passes it on to the processor's interrupt line. The processor in turn shifts its focus to the incoming keystrokes and handles them in the prescribed manner. There is a pre-determined routine to be followed by the system for each of the PC's interrupt lines.

Two things of note should be remembered when reading this. One is that there is really a lot more involved than just the few simple steps that I've described here; the process was simplified for this discussion by stripping it down to just its pertinent factors. The other is that this all occurs at incredibly high rates of speed - thousands of times per second. Consider the concept of a 200 MHz CPU that can process 20 million instructions between each keystroke of 120 word-per-minute typist, based on an average of five characters per word.

OK, so now that we have seen the basics of interrupt operation, we should look at some more detail about their deployment in the system. The original PC and XT systems used 8-bit ISA expansion slots, and had eight hardware interrupt lines. Figure 1 below shows the default IRQ assignments for the XT-class machines.

Note that not all of the interrupt lines were made available to the expansion bus. Only those IRQ's that are available to the bus can be used by expansion devices installed to the bus. In other words, no user-installed expansion card could be assigned either IRQ0 or IRQ1, as there were no connections for those IRQ's assigned in the ISA 8-bit expansion slot.

In earlier (pre-AT) systems, IRQ2 was reserved for certain video adapter types. With the introduction of the 16-bit ISA bus and the VGA standard, that reservation was pretty much no longer needed, but there was a need for additional IRQ lines. In keeping with the desire for backward compatibility, the engineers devised a scheme that would allow the additional IRQ lines to have processor access without changing the basic structure already in place. The result was the cascaded IRQ's numbered 8 through 15. These newly created IRQ's are connected to the CPU through the basically unused IRQ2 connection.

The existing IRQ2 line was removed from the 8-bit ISA slot and made available as a motherboard connection. A second Intel 8259A chip was added as a controller for the new IRQ's. Its output line connects to the IRQ2 line on the primary 8259A controller as an input. The line designated as IRQ9 on the new controller was then connected to the former IRQ2 connector on the 8-bit ISA slot. Most of the remaining IRQ lines of the secondary 8259A were then brought out to connections on the new 16-bit extension portion of the ISA expansion slot. Thus, we now have fifteen unique interrupt lines communicating to the CPU via the path that previously supported 8 interrupt lines. Figure 2 shows the default IRQ assignments for the AT-class machines.

There is a certain amount of prioritization that occurs due to IRQ lines, but the effect of this prioritization is not really noticeable on today's high-speed computers. In a nutshell, the CPU responds to IRQ signals in their numerical order. In other words, if two devices apply an IRQ signal simultaneously, the device with the lower IRQ number gets the CPU's attention first. However, there is a catch to this scheme, which is hinted at in Figure 2. All of the interrupts handled by the second IRQ controller are prioritized after IRQ1 (the keyboard), but before IRQ3 (COM2:). This is due to the fact that they are connected to the first IRQ controller in place of the original IRQ2, and the entire second controller has therefore inherited the old IRQ2 priority position.

Your PC has a limited number of IRQ's available - effectively fifteen on a modern system. Of these fifteen existing IRQ's, several are permanently assigned to specific mainboard devices and cannot be used for other purposes. The following chart (Figure 3) shows the typical IRQ assignments in use today. Note that some of the assignments are flexible (indicated by *), while others cannot be changed.

IRQ Line Typical Device Comments and Probable User Assignments

As can be seen in the chart, there are basically four IRQ's to choose from when installing additional devices into a standard PC. That's not a whole lot to work with! Now consider all of the devices that are found in most new PC's today. What happens when you try to add a modem, a sound card, a network adapter, a SCSI card, and a second printer port? A long-standing problem has been that two devices cannot share a single IRQ and have both devices work properly at the same time. We simply have more devices requiring IRQ's than we have available IRQ lines to assign! The engineers solved this dilemma with the introduction of the PCI (Peripheral Component Interconnect) bus.

For the first time, the PCI bus allowed for managed sharing of hardware interrupts. We can now have multiple PCI devices assigned to the same physical IRQ line, because the PCI chipset manages communication between the PCI devices and the processor. For this reason, it is perfectly normal today to see two or three devices assigned to the same IRQ. In this case, you will also see entries such as IRQ Holder for PCI Steering.

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Posted: 2008-02-15 By: FortyPoundHead Viewed: 2,842 times

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RFB posted this comment on 2019-05-25:

I replaced a failed CRT with a LCD panel with VGA controller. With the single board computer on the bench the display is perfect in all respects. With the single board computer in machine the display is perfect until I switch the screen off and on. That raises an 'Out of Range' error. The only difference between the bench and the machine is that the machine has an ISA board installed. Does that appear to be a hardware conflict? If so then can it be resolved?

dwirch posted this comment on 2019-05-26:

Have you tried removing the ISA board and repeating the process?  If the same behavior is experienced, then it's not the ISA board. 

Sorry. Comments are frozen for this article. If you have a question or comment that relates to this article, please post it in the appropriate forum .

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Motherboards Help me understand IRQ assignments on Asus motherboard

Discussion in ' Hardware ' started by Chicken76 , 3 Oct 2012 .

Chicken76 Minimodder

Board in question is Asus P8Z77-V If you look in the manual at page 2-13 there is a table called IRQ assignments for this motherboard What I don't understand is what are the A B C ... H columns?  

Guest-16 Guest

I'm not sure either but why do you need to assign IRQs? EDIT: Oh I think they can be assigned to any IRQ, but all under a particular column will be shared whatever the number.  

I don't need to assign IRQs manually. I just need to populate at least 3 PCI-E slots and also use (some of) the USB ports and the integrated NIC. And not having shared interrupts will be a big plus for me. I also initially considered what you said, but for some scenarios it just doesn't make sense. Take column C for example, you'd think no slots are populated, only ASMedia USB controller is turned on, and it will have it's interrupt shared, right? But with whom? Or column A, you have the interrupt of your discrete video card shared with the third PCI-E 16x slot (meh...), a PCI slot and also two USB controllers?! So if you have USB mouse and keyboard and a USB or PCI sound card/amp then you can kiss smoothness goodbye in (for example) any demanding 3D game? I feel we're not interpreting the table correctly, or some information was left out of the manual somehow.  

Phalanx Needs more dragons and stuff.

IRQ interrupts are best left to the OS, trust me. You do NOT want to go prodding, unless you fancy going back to the age of Windows 3.11-95.  

faugusztin I *am* the guy with two left hands

Chicken76 said: ↑ I also initially considered what you said, but for some scenarios it just doesn't make sense. Take column C for example, you'd think no slots are populated, only ASMedia USB controller is turned on, and it will have it's interrupt shared, right? But with whom? Click to expand...

Chicken76 said: ↑ I don't need to assign IRQs manually. I just need to populate at least 3 PCI-E slots and also use (some of) the USB ports and the integrated NIC. And not having shared interrupts will be a big plus for me. I also initially considered what you said, but for some scenarios it just doesn't make sense. Take column C for example, you'd think no slots are populated, only ASMedia USB controller is turned on, and it will have it's interrupt shared, right? But with whom? Or column A, you have the interrupt of your discrete video card shared with the third PCI-E 16x slot (meh...), a PCI slot and also two USB controllers?! So if you have USB mouse and keyboard and a USB or PCI sound card/amp then you can kiss smoothness goodbye in (for example) any demanding 3D game? I feel we're not interpreting the table correctly, or some information was left out of the manual somehow. Click to expand...

Alright, thanks guys. Have some rep.  

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What Is an IRQ (Interrupt Request)?

Devices send an IRQ to the processor to request access

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Purpose of IRQ

• Viewing and Editing IRQ Settings

How to Change IRQ Settings

Common irq channels, what are non-maskable interrupts.

An IRQ, short for Interrupt Request, is used in a computer to send exactly that—a request to interrupt the CPU by some other piece of hardware .

An Interrupt Request is necessary for things like keyboard presses, mouse movements, printer actions, and more. When the request is made by a device to momentarily stop the processor, the computer is then able to give the device some time to run its own operation.

For example, each time you press a key on the keyboard, an interrupt handler tells the processor that it needs to stop what it's currently doing so that it can handle the keystrokes.

Each device communicates the request over a unique data line called a channel. Most of the time you see IRQ referenced, it's alongside this channel number, also called an IRQ number . For example, IRQ 4 might be used for one device and IRQ 7 for another.

IRQ is pronounced as the letters I-R-Q, not as  erk .

Errors related to Interrupt Request are usually only seen when installing new hardware or changing the settings in existing hardware. Here are some IRQ errors you might see:

See How to Fix a Blue Screen of Death  if you're experiencing either of those stop errors .

While it's possible for the same IRQ channel to be used for more than one device (so long as both aren't actually being used at the same time), it's normally not the case. An IRQ conflict most likely occurs when two pieces of hardware are attempting to use the same channel for an interrupt request. 

Since the Programmable Interrupt Controller (PIC) doesn't support this, the computer might freeze up or the devices will stop working as expected (or stop working entirely).

Back in the early Windows days, IRQ errors were common, and it took a lot of troubleshooting to fix them. This is because it was more common to set IRQ channels manually, like with DIP switches, which made it more likely that more than one device was using the same IRQ line.

However, IRQs are handled much better in newer versions of Windows that use plug and play , so you'll rarely see an IRQ conflict or other IRQ issue.

Viewing and Editing IRQ Settings

The easiest way to view IRQ information in Windows is with  Device Manager . Change the  View  menu option to  Resources by type  to see the  Interrupt request (IRQ)  section.

You can also use System Information. Execute the  msinfo32.exe  command from the Run dialog box ( WIN+R ), and then go to  Hardware Resources > IRQs .

Linux users can run the  cat /proc/interrupts  command to view IRQ mappings.

You might need to change the IRQ line for a specific device if it's using the same IRQ as another, though it's usually unnecessary since  system resources  are automatically allocated for newer devices. It's only older Industry Standard Architecture (ISA) devices that might need manual IRQ adjustments.

You can change IRQ settings in the BIOS  or within Windows via Device Manager. Here's how to change IRQ settings with Device Manager:

Remember that making incorrect changes to these settings can cause problems you didn't have before. Make sure you know what you're doing and have recorded any existing settings and values so that you know what to revert to should something go wrong.

Open Device Manager and double-click or double-tap a device to open its  Properties  window. You'll need to open that device's category first before you'll be able to see it, which you can do by double-clicking/tapping.

In the  Resources  tab, deselect Use automatic settings .

If you can't find this tab or the option is greyed out or not enabled, it means that either you cannot specify a resource for that device or that the device has no other settings that can be applied to it.

Use the Settings based on drop down menu to select the hardware configuration that should be changed.

Select IRQ from the Resource settings area of the properties.

Use the  Change Setting button to edit the IRQ value.

Here are what some of the more common IRQ channels are used for:

Since IRQ 2 has a designated purpose, any device configured to use it will instead use IRQ 9.

There are also non-maskable interrupts (NMIs), which are interrupt requests that can't be blocked. A non-maskable interrupt occurs when dealing with system resets or hardware errors. The interrupt request is executed immediately.

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IRQs Explained

All computers do one thing very well…they follow instructions. Each instruction has a length and an address. The instruction pointer contains the address of the next instruction to be executed, and as soon as it has begun execution, the IP is incremented by the length of that instruction, thereby pointing to the next one, and so on. Some instructions can modify this address, and are called ‘branch’ instructions because they cause the computer to branch to a different piece of the program. This sequence of events will occur until something comes along that causes the computer to break away – which is called an ‘interrupt’.

The architecture of the computer will determine the type and number of interrupts that are recognized. Interrupts essentially cause the computer to save off the current instruction pointer (and associated flags, registers, etc.) and replace it with another address that will execute a completely different program. That program might be another ‘task’ (which is how multi-tasking is performed), might be an operating system routine (such as a DOS or BIOS interrupt), might be some recovery or termination code (such as a system error routine to dump addresses), or might be some routine that interfaces with a piece of hardware. In addition, interrupts can be classed as ‘maskable’ (can be ignored) or ‘non-maskable’ (must be acted upon immediately). It is possible that a maskable interrupt could be pre-empted by another interrupt if it is not acted upon quickly enough.

The Interrupt Vector Table

The interrupt table is a list of addresses which contain the information about which routine gets executed when that interrupt has been recognized, and is officially known as the Interrupt Vector Table. There is a special set of signal lines to the CPU which signal when an interrupt has been requested. The CPU checks the opcode and type, determines whether it should honor the interrupt immediately (or wait for a more convenient time), and then locates the address of the routine to be executed if it determines that the interrupt should be taken. The address is basically the interrupt number multiplied by 4. This is because each address is 4-bytes long, and the vector table begins at address ‘0’. The table is 256 entries long, or 1024 bytes (0400 in hex).

When the system is first initialized (boot up), the Interrupt Vector Table is initialized. Many of these routines are pre-defined by the architecture of the machine, but a few are reserved, and therefore can be used by hardware and software manufacturers. These ‘user defined’ interrupts are loaded immediately after the nucleus or kernel is loaded, and before any application level programs are loaded. For this reason, any device or software requiring an interrupt cannot be made active without rebooting the machine and initializing it’s interrupt address.

For the most part IRQs cannot be shared. The only exception to this is where two devices can use the exact same interrupt routine (such as serial devices), and do not have to operate at the same time. If this rule is violated, either one (or both) devices will not work, the machine will lock up, or in the most extreme situation the system will not even complete the boot up routines.

Assigning IRQs

As it turns out, Plug’N Play is one of the most frustrating issues we have encountered in hardware configuration. The intention was to have the hardware and the operating system ‘negotiate’ for an available IRQ. The theory was that most people did not understand IRQs, and so the more intelligent engineers would handle this difficult situation ‘under the covers’. Well, it hasn’t quite worked out that way. Most PnP devices no longer have jumpers to override the ‘firmware’ IRQ assignments, and the PnP operating systems (like Win95), don’t use configurable drivers. The result is multiple devices trying to use the same IRQ – especially sound cards and modems. Fortunately, there are still several ways to assign IRQs for yourself.

The best method for manually assigning IRQs (if available) is through the BIOS. Many of the more recent BIOS programs have a menu selection which allows you to avoid any Plug’N Play assignments for specific IRQs. They will typically have a list of all 16 IRQs, with the default setting as ‘No/ICU’, which means that it is *not* reserved, and can be assigned by the Interrupt Controller Utility. The other option is ‘Legacy ISA’, which means that the system is to reserve this IRQ for use by non-PnP (or Legacy) devices.

Windows95 also allows the re-assignment of IRQs through the Device Manager. By opening the Control Panel and selecting the System icon, you will be presented with a screen with a Device Manager tab on the top. When you select this tab, you will be presented with a list of all the defined device types (such as ‘display controller’, ‘sound cards’, ‘modems’, etc.), with the highest level device being labeled ‘Computer’. If you highlight this device, and click on ‘Properties’, you will be presented with a list of every IRQ that is currently in use – including any duplicates. If you see a ‘!’ (exclamation point) next to any IRQ number, this means that either the IRQ is in use by another device, or the Win95 driver which assigns this IRQ has not been loaded properly.

Next to each of the other device types will usually be a ‘+’, which means there are devices defined under this type. If you click on the ‘+’, these devices will be displayed. By highlighting the device you wish to view/configure, and clicking on the ‘Properties’ button, you will be presented with another screen. Usually there will be a ‘Resources’ tab, that will show the IRQ and port address for the device (port addresses will be discussed in a future article). Some devices will let you highlight the IRQ number and change it, while others will not. If the check box labeled ‘manually configure’ is not grayed out, you can check it, and then change the IRQ number that way. Beware, however, that using this method may hamper the automatic configuration of any new PnP devices you install. If that box is grayed out, you cannot change the IRQ through Win95 and must use the BIOS method described above.

Once you have made these changes, you will need to reboot the machine so that the correct addresses can be loaded, and the device can be made available to the system. Occasionally you will need to perform this routine several times before you get everything configured properly. Sometimes, however, the mix of hardware simply will not allow everything to be installed together. When this happens, your only choices are to do without one (or more) of the components, or use some ‘IRQ saving’ techninques (which usually means buying different hardware, unfortunately).

Saving IRQs

There are a few things that can be done to reduce the number of IRQs that are required. If you don’t need both on board serial ports, you can disable one or both of them and free up IRQ3 and/or IRQ4. On the other hand, you might attach an external modem and utilize COM2, making IRQ5 available for another device. By the same token, you might use a PS/2 mouse connector (if available for your motherboard), and free up COM1 for attaching a scanner or other external serial device.

A little more expensive solution is to plug in a SCSI adapter, and connect SCSI devices, such as hard drives and scanners. If you disable the onboard IDE controllers, you can then use IRQ14 and IRQ15 for something else. Since SCSI controllers can attach up to 15 devices, yet only take one IRQ, you have much more device ‘real estate’ available to you. One final option that may soon be more widely available is the use of USB devices, which may include keyboards, mice and other low-throughput devices.

With a little understanding of how IRQs work, and some judicious use of the techniques mentioned here, you should be able to overcome just about any IRQ problems you may encounter. Until the architecture of the PC is completely revamped (which means scrapping our current operating systems, hardware, etc. – so don’t hold your breath), we will be stuck with the limited number of IRQs currently available. It is possible that a few more might be squeezed out of the architecture, but not very likely. The most probable long term solution will be the development of fast serial devices on Firewire (IEEE 1394) connections, such as hard drives, tape drives, monitors, scanners, modems, etc.

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What is an interrupt request (IRQ) and how does it relate to computing?

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An IRQ is a fundamental mechanism in computing that allows devices to interrupt the central processing unit (CPU) when they need attention or action. When a device generates an IRQ, it suspends the CPU's current task to process the interrupt and respond accordingly.

What is the purpose of IRQs in technology?

IRQs play a crucial role in managing hardware interactions in computers. They enable devices like keyboards, mice, network cards, and more to signal the central processing unit (CPU) when they have data to transfer or require processing. This way, the CPU efficiently handles multiple tasks and ensures devices work harmoniously.

How many IRQ lines are typically available on a computer system?

Traditional systems have 16 IRQ lines (0 to 15), allowing up to 16 different hardware devices to request central processing unit (CPU) attention independently. With newer systems and advanced architectures, the number of IRQs can vary, but they are still essential for hardware coordination.

What happens when multiple devices attempt to use the same IRQ?

If multiple devices share the same IRQ, conflicts can occur, leading to malfunctions or instability. This issue is known as an IRQ conflict, and it can be resolved by reassigning IRQs or adjusting the hardware configuration.

Does IRQ sharing impact system performance?

Yes, IRQ sharing can affect system performance, especially if two essential devices, such as a graphics card and a sound card, share the same IRQ. This situation can lead to reduced performance or latency issues. Modern systems use advanced techniques to minimize IRQ sharing.

What are the common methods to view IRQ assignments in an operating system?

In Windows, you can check IRQ assignments through the Device Manager. Open it, locate the device of interest, right-click, choose "Properties," go to the "Resources" tab, and view the IRQ information. On Linux®, you can use terminal commands like cat /proc/interrupts to see IRQ details.

What happens during an IRQ handling process?

When an IRQ is triggered, the central processing unit (CPU) halts its current operation, saves the current context, and jumps to the corresponding IRQ handler routine. The handler processes the interrupt, saves necessary data, performs actions as required, and then restores the CPU context to resume normal execution.

Are all IRQs generated by external hardware devices?

No, not all IRQs are generated by external hardware. Some IRQs can be internally generated by the central processing unit (CPU) to signal critical events or errors. These internal IRQs are essential for system stability and error handling.

What do I mean by cascading IRQs in computer systems?

Cascading IRQs involve using one IRQ line to manage several IRQs simultaneously. In older systems with limited IRQ lines, this technique allowed multiple devices to share a single IRQ. However, modern systems and advanced architectures have made cascading IRQs less common.

How does a device request an IRQ from the central processing unit (CPU)?

When a device requires CPU attention, it sends a signal through its IRQ line to the interrupt controller. The interrupt controller then prioritizes the requests and informs the CPU, which suspends its current task and handles the interrupt according to its priority.

What are the advantages of using IRQs for hardware communication?

IRQs offer several advantages, including efficient central processing unit (CPU) utilization, low latency for time-sensitive tasks, and the ability to handle various devices simultaneously. They ensure smooth data flow between hardware and the CPU, making the system more responsive and capable of multitasking.

Does the order of IRQ priority affect device performance?

Yes, the order of IRQ priority can impact device performance. Higher-priority devices get faster access to the central processing unit (CPU), leading to reduced latency and quicker responses. Adjusting IRQ priorities can optimize system performance, particularly in scenarios where low latency is crucial.

How can I identify IRQ bottlenecks that affect system performance?

You can use various tools and monitoring utilities to identify IRQ bottlenecks. Performance monitoring software like Task Manager in Windows or top in Linux® can help you track central processing unit (CPU) usage and IRQ activity. If a specific IRQ shows unusually high usage, it may indicate a bottleneck.

How is the concept of IRQ related to real-time operating systems (RTOS)?

In real-time operating systems, IRQs are crucial for time-critical tasks. Devices like sensors or actuators generate interruptions, and the RTOS must handle them promptly to meet strict timing requirements. RTOS designs carefully prioritize and manage IRQs to ensure timely and predictable responses.

Can IRQs be reassigned manually in Linux®?

Yes, in Linux®, IRQs can be manually reassigned through the kernel's advanced configuration and power interface (ACPI) tables. However, manual IRQ reassignment requires a thorough understanding of the system and should be attempted by experienced users to avoid potential issues.

What role does the basic input/output system (BIOS) play in managing IRQs?

BIOS handles hardware initialization, including managing IRQ assignments during the boot process. It sets up the interrupt controllers and configures IRQ priorities, ensuring a stable hardware environment for the operating system to function correctly.

How can I optimize IRQ handling for better system performance?

To optimize IRQ handling, ensure your hardware drivers are up to date, and the basic input/output system (BIOS) is running the latest version. Avoid unnecessary hardware, as it reduces IRQ conflicts. Consider using message signaled interrupt (MSI/MSI-X) if supported, and monitor system performance to identify and resolve any IRQ-related issues promptly.

How do modern operating systems handle IRQ management compared to older ones?

Modern operating systems have advanced IRQ management techniques to reduce conflicts and improve performance. They use techniques like plug and play (PnP) to automatically detect and configure hardware, dynamically assign IRQs to devices, and utilize message signaled interrupt (MSI/MSI-X) for direct interrupt delivery, reducing the need for IRQ sharing.

Can IRQs be virtualized in virtual machine environments?

Yes, IRQ virtualization is possible in virtual machine (VM) environments. Virtualization software, like VMware or VirtualBox, can emulate virtual IRQs for the VM's devices. The host operating system (OS) manages the physical IRQs, while the guest OS inside the VM handles the virtual IRQs.

Can I manually set IRQ priorities in the basic input/output system (BIOS) for better performance?

While some BIOS versions allow manual IRQ priority adjustments, it is generally not recommended for average users. Incorrect settings may lead to system instability or failures. Modern systems handle IRQ priorities automatically, and tampering with these settings can cause more harm than good.

Can IRQ sharing cause performance issues in multi-graphics processing unit (GPU) configurations?

In multi-GPU configurations, IRQ sharing can lead to performance issues. Each GPU might require dedicated bandwidth to communicate with the central processing unit (CPU). Sharing IRQs between GPUs and other devices can create bottlenecks and hamper performance. Ensuring proper IRQ allocation can optimize multi-GPU setups.

What is the impact of IRQ handling on power consumption?

IRQ handling can impact power consumption in computing systems. Excessive IRQ activity, particularly when dealing with poorly optimized drivers or malfunctioning devices, can result in higher central processing unit (CPU) usage, leading to increased power consumption. Efficient IRQ management helps conserve power and prolong battery life in mobile devices.

Can IRQs be shared between different processor cores in a multi-core system?

Yes, IRQs can be shared between different processor cores in a multi-core system. Modern interrupt controllers support distributing interrupts across cores to optimize central processing unit (CPU) usage. This capability enhances performance by allowing multiple cores to process IRQs simultaneously.

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Asus Motherboard 1.8.3Interrupt assignments, Standard interrupt assignments, IRQ assignments for this motherboard, *These IRQs are usually available for ISA or PCI devices

1 . 8 . 3 I nterrupt ass i gnments

Standard i nterrupt ass i gnments.

0 System Timer

1 Keyboard Controller

2 Re-direct to IRQ#9

4 Communications Port (COM1)*

5 IRQ holder for PCI steering*

6 Floppy Disk Controller

7 Printer Port (LPT1)*

8 System CMOS/Real Time Clock

9 IRQ holder for PCI steering*

10 IRQ holder for PCI steering*

11 IRQ holder for PCI steering*

12 PS/2 Compatible Mouse Port*

13 Numeric Data Processor

14 Primary IDE Channel

* These IRQs are usually available for ISA or PCI devices.

I rq ass i gnments for th i s motherboard.

When using PCI cards on shared slots, ensure that the drivers support “Share IRQ” or that the cards do not need IRQ assignments. Otherwise, conflicts will arise between the two PCI groups, making the system unstable and the card inoperable.

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ARCHIVED: On a PC, what is an Interrupt Request number?

An Interrupt Request is a signal from a hardware device on your computer to your CPU. When a hardware device needs the CPU to do something (such as move the cursor as you move the mouse), the device sends an Interrupt Request to the CPU. Since a CPU can get several of these Interrupt Requests at once from various devices along the same path (e.g., the serial port or the PCI bus), it needs a way to distinguish between them. To do so, the computer assigns an Interrupt Request number (the IRQ number) to each device and its path to the CPU.

The Interrupt Request made through the device's IRQ number signals the CPU that the device has a request that needs processing. (A hardware device that needs attention from the CPU is often referred to as "needing servicing".) IRQ numbers are assigned during the boot process to each hardware device that needs one.

A device requires an IRQ number if it is able to provide input to the CPU or start an action. The IRQ number is a numeric way to assign the priority that the devices have with the CPU. The lower the value of the IRQ number, the more important the need for the input or action to take place. Some devices that are assigned IRQ numbers include the disk drive controllers (floppy and hard disk), mouse, keyboard, and sound card.

An IRQ conflict happens when two devices attempt to use the same IRQ number, and the operating system or motherboard has no mechanism for accommodating this. These conflicts were common in older versions of Windows, but occur only rarely in modern versions of the operating system. IRQ conflicts result in errors because the CPU can't figure out which device really owns the IRQ number. An IRQ conflict can cause problems severe enough to freeze, or lock up, your computer.

However, since the introduction of Windows 2000 , true IRQ conflicts have been extremely rare, for the reasons listed below. Due to advances in the operating system, the old advice about IRQ sharing that was applied to Windows 95 , 98 , Me , and NT no longer holds true; that is, you should not attempt to solve IRQ conflicts in Windows 2000 and XP by manually assigning devices different IRQ numbers, as those devices are supposed to be sharing IRQ numbers. In Windows 2000 and XP, manually forcing IRQ assignments will interfere severely with how the operating system works.

To correct an IRQ conflict in an older version of Windows, you will need to change the IRQ number on one of the devices to an unused IRQ number. You can make this correction one of several ways, including changing jumpers or micro-switch positions on the device, making changes in the software setup for the device, or making changes in the device manager. For more information, see ARCHIVED: In Windows, what is the Device Manager, and how can I use it?

IRQ conflicts are less of an issue with modern versions of Windows for the following reasons:

• The introduction of PCI/IRQ steering in Windows 95 OSR2 provided a mechanism for graceful sharing of IRQs between devices.
• The full acceptance of Plug and Play by hardware manufacturers led them to design their devices and drivers to be more flexible about the IRQs they would accept.
• The continual development of the Advanced Configuration and Power Interface standard ( ACPI ) has allowed the development of motherboard BIOSes and operating systems that accept IRQ numbers above 15.

In Windows 2000 and XP, with motherboards that have an Advanced Programmable Interrupt Controller (APIC), up to 24 IRQs are available. The ACPI standard itself theoretically allows for up to 255 virtual interrupts by mapping a virtual interrupt table to a single IRQ (usually IRQ 9 or 11), and letting Windows rather than the BIOS determine the priority of a device's interrupt request.

Typical IRQ assignments for a PC

The list below indicates some of the typical IRQ assignments for a PC:

This is document ailq in the Knowledge Base. Last modified on 2018-01-18 12:46:12 .

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Asus P5QL Manual

• Manual (64 pages)
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Table of Contents

• Federal Communications Commission Statement
• Canadian Department of Communications Statement
• Safety Information
• Electrical Safety
• About this Guide
• Conventions Used in this Guide
• P5QL-EM Specifications Summary
• Chapter 1 Product Introduction
• Package Contents
• Special Features
• Product Highlights
• ASUS Special Features
• Before You Proceed
• Onboard LED
• Motherboard Overview
• Placement Direction
• Screw Holes
• Motherboard Layout
• Central Processing Unit (CPU)
• Installling the CPU
• Installling the CPU Heatsink and Fan
• Uninstalling the CPU Heatsink and Fan
• System Memory
• Memory Configurations
• DDR2 Qualified Vendors List
• Installing a DIMM
• Removing a DIMM
• Expansion Slots
• Installing an Expansion Card
• Configuring an Expansion Card
• Interrupt Assignments
• Irq Assignments for this Motherboard
• PCI Express X1 Slot
• PCI Express X16 Slot
• Clear RTC RAM
• 1.10 Connectors
• Rear Panel Connectors
• Internal Connectors
• IDE Connectors
• System Panel Connector
• Chapter 2 BIOS Setup
• Managing and Updating Your BIOS
• Creating a Bootable Floppy Disk
• ASUS EZ Flash 2 Utility
• AFUDOS Utility
• ASUS Crashfree BIOS 3 Utility
• ASUS Update Utility
• BIOS Menu Screen
• Navigation Keys
• Sub-Menu Items
• Configuration Fields
• Pop-Up Window
• General Help
• System Time
• System Date
• Legacy Diskette a
• Storage Configuration
• System Information
• Advanced Menu
• Jumperfree Configuration
• CPU Configuration
• South Bridge Configuration
• Onboard Devices Configuration
• USB Configuration
• Suspend Mode
• ACPI 2.0 Support
• ACPI APIC Support
• APM Configuration
• Hardware Monitor
• Boot Device Priority
• Boot Settings Configuration
• Change User Password
• Clear User Password
• ASUS EZ Flash 2
• Express Gate
• Chapter 3 Software Support
• Installing an Operating System
• Support DVD Information
• Running the Support DVD
• Drivers Menu
• Utilities Menu
• Manual Menu
• ASUS Contact Information
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• Technical Support Form
• ASUS Express Gate
• Appendix Cpu Features
• Enhanced Intel Speedstep Technology (EIST)
• System Requirements
• Using the EIST
• Intel ® Hyper-Threading Technology
• Using the Hyper-Threading Technology

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• Page 1 P5QL-EM...
• Page 2 Product warranty or service will not be extended if: (1) the product is repaired, modified or altered, unless such repair, modification of alteration is authorized in writing by ASUS; or (2) the serial number of the product is defaced or missing.

Page 3: Table Of Contents

• Page 4 Chapter 2 BIOS setup Managing and updating your BIOS ..........2-2 2.1.1 Creating a bootable floppy disk ........2-2 2.1.2 ASUS EZ Flash 2 utility ........... 2-4 2.1.3 AFUDOS utility ..............2-5 2.1.4 ASUS CrashFree BIOS 3 utility ........2-7 2.1.5 ASUS Update utility ............
• Page 5 Boot Device Priority ............2-34 2.6.2 Boot Settings Configuration .......... 2-35 2.6.3 Security ................. 2-36 Tools menu ................. 2-38 2.7.1 ASUS EZ Flash 2 ............2-38 2.7.2 Express Gate ..............2-39 2.7.3 AI NET 2................ 2-39 Exit menu ..................2-40 Chapter 3 Software support Installing an operating system ...........

Page 6: Notices

Page 7: safety information, page 8: about this guide, page 9: conventions used in this guide, page 10: p5ql-em specifications summary.

• Page 11 ASUS overclocking SFS (Stepless Frequency Selection): features - FSB turning from 200MHz up to 600MHz at 1MHz increment ASUS C.P.R. (CPU Parameter Recall) ASUS Special Features ASUS CrashFree BIOS 3 ASUS Q-Fan ASUS EZ Flash 2 ASUS MyLogo 2...
• Page 12 P5QL-EM specifications summary BIOS features 8 MB Flash ROM, AMI BIOS, Special H/W write protection, PnP, DMI v2.0, WfM2.0, SMBIOS 2.5, ACPI Manageability WOL by PME, WOR by PME, WOR by Ring Support DVD Drivers ASUS PC Probe II ASUS LiveUpdate Utility...

Page 13: Chapter 1 Product Introduction

Page 14: welcome.

• Page 15 Dual channel DDR2 1066(O.C.) ASUS P5QL-EM...

Page 16: Asus Special Features

• Page 17 ASUS CrashFree BIOS 3 The ASUS CrashFree BIOS 3 allows users to restore corrupted BIOS data from a USB flash disk containing the BIOS file. This utility saves users’ the cost and hassle of buying a replacement BIOS chip. ASUS Express Gate Taking only 5 seconds to go online from bootup, Express Gate is the one-stop gateway to instant fun! It’s a unique motherboard built-in OS.

Page 18: Before You Proceed

Page 19: motherboard overview, page 20: motherboard layout, page 21: central processing unit (cpu).

• Page 22 To prevent damage to the socket pins, do not remove the PnP cap unless you are installing a CPU. 1-10 Chapter 1: Product introduction...
• Page 23 If so, skip this step. The Thermal Interface Material is toxic and inedible. If it gets into your eyes or touches your skin, ensure to wash it off immediately, and seek professional medical help. ASUS P5QL-EM 1-11...

Page 24: Installling The Cpu Heatsink And Fan

• Page 25 When the fan and heatsink assembly is in place, connect the CPU fan cable to the connector on the motherboard labeled CPU_FAN. CPU_FAN P5QL-EM CPU Fan Connector • Do not forget to connect the CPU fan connector! Hardware monitoring errors can occur if you fail to plug this connector.

Page 26: Uninstalling The Cpu Heatsink And Fan

Page 27: system memory, page 28: memory configurations, page 29: ddr2 qualified vendors list.

• Page 30 DIMM support Size Vendor Part No. Chip Brand Chip No. 667 1G Super Talent T667UB1GV Super Talent PG 64M8-800 0750 • • 512MB Twinmos 8D-A3JK5MPETP A3R12E3GEF633ACAOY • • • Samsung M378T5263AZ3-CE6 Samsung K4T2G084QA-HCE6 • • Kingtiger E0736001024667 Kingtiger KTG667PS6408NST-C6 GDBTX •...
• Page 31 • • Super Talent T800UB1GC4 Super Talent Heat-Sink Package • • G.SKILL F2-6400CL5D-2GBNQ G.SKILL Heat-Sink Package • • G.SKILL F2-6400CL4D-2GBPK G.SKILL Heat-Sink Package • • G.SKILL F2-6400CL4D-2GBHK G.SKILL Heat-Sink Package • • (continued on the next page) ASUS P5QL-EM 1-19...
• Page 32 (supports two DIMM modules only for yellow DIMMs when overclock to DDR2-1066). • C*: Supports 4 modules inserted into both the yellow and black slots as two pairs of Dual-channel memory configuration. Visit the ASUS website for the latest DDR2-667/800/1066 MHz QVL. 1-20 Chapter 1: Product introduction...

Page 33: Installing A Dimm

Page 34: expansion slots, page 35: interrupt assignments, page 36: irq assignments for this motherboard, page 37: pci slot, page 38: jumpers.

• Page 39 USBPW1-4 PS2_USBPW5-6 USBPW78 USBPW9-12 P5QL-EM USB Device Wake Up • The USB device wake-up feature requires a power supply that can provide 500mA on the +5VSB lead for each USB port; otherwise, the system would not power up.

Page 40: 1.10 Connectors

• Page 41 RGB Signal to CRT and isn’t compatible with DVI-I. 15. HDMI port. This port is for a High-Definition Multimedia Interface (HDMI) connector, and is HDCP compliant allowing playback of HD DVD, Blu-Ray and other protected content ASUS P5QL-EM 1-29...
• Page 42 • This motherboard comes with dual-VGA output. If you connect 2 monitors to both VGA and DVI-D / HDMI out ports, each controller can drive same or different display contents to different resolutions and refresh rates. • To play HD DVD or Blu-Ray Disc, ensure to use an HDCP compliant monitor.

Page 43: Internal Connectors

Page 44: ide connectors.

• Page 45 These are not jumpers! DO NOT place jumper caps on the fan connectors. P5QL-EM Fan Connectors Digital Audio connector (4-1 pin SPDIF_OUT) This connector is for the S/PDIF audio module to allow digital sound output.
• Page 46 350 W. The system may become unstable or may not boot up if the power is inadequate. • You must install a PSU with a higher power rating if you intend to install additional devices. EATXPWR P5QL-EM ATX Power Connector 1-34 Chapter 1: Product introduction...
• Page 47 HD Audio or legacy AC’97 audio standard. AAFP HD-audio-compliant Legacy AC’97 compliant definition pin definition P5QL-EM Front Panel Audio Connector • We recommend that you connect a high-definition front panel audio module to this connector to avail of the motherboard’s high-definition audio capability. •...
• Page 48 P5QL-EM Intrusion Connector 10. USB connectors (10-1 pin USB1112, USB910, USB78) USB1112 USB910 USB78 P5QL-EM USB 2.0 Connectors Never connect a 1394 cable to the USB connectors. Doing so will damage the motherboard! The USB module is purchased separately. 1-36...
• Page 49 The serial port bracket (COM1) is purchased separately. COM1 P5QL-EM COM Port Connector 12. LPT connector (26-1 pin LPT) The LPT (Line Printing Terminal) connector supports devices such as a printer. LPT standardizes as IEEE 1394, which is the parallel port interface on IBM PC-compatible computers.

Page 50: System Panel Connector

Page 51: chapter 2 bios setup, page 52: managing and updating your bios.

• Page 53 Right-click Floppy Disk Drive then click Format to display the Format 3 1/2 Floppy dialog box. d. Select the Create an MS-DOS startup disk check box. e. Click Start. Copy the original or the latest motherboard BIOS file to the bootable floppy disk. ASUS P5QL-EM...

Page 54: Asus Ez Flash 2 Utility

Page 55: afudos utility.

• Page 56 Updating the BIOS file To update the BIOS file using the AFUDOS utility: Visit the ASUS website (www.asus.com) and download the latest BIOS file for the motherboard. Save the BIOS file to a bootable floppy disk. Write the BIOS filename on a piece of paper. You need to type the exact BIOS filename at the DOS prompt.

Page 57: Asus Crashfree Bios 3 Utility

• Page 58 Restart the system after the utility completes the updating process. • Only the USB flash disk with FAT 32/16 format and single partition can support ASUS CrashFree BIOS 3. The device size should be smaller than 8GB. • DO NOT shut down or reset the system while updating the BIOS! Doing so...

Page 59: Asus Update Utility

• Page 60 To update the BIOS through the Internet: desktop by clicking Start Launch the ASUS Update utility from the Windows ® > Programs > ASUS > ASUSUpdate > ASUSUpdate. The ASUS Update main window appears. Select Update BIOS from Select the ASUS FTP site nearest...
• Page 61 Updating the BIOS through a BIOS file To update the BIOS through a BIOS file: Launch the ASUS Update utility from the Windows® desktop by clicking Start > Programs > ASUS > ASUSUpdate > ASUSUpdate. The ASUS Update main window appears.
• Page 62 The BIOS setup screens shown in this section are for reference purposes only, and may not exactly match what you see on your screen. • Visit the ASUS website (www.asus.com) to download the latest BIOS file for this motherboard. 2-12...

Page 63: Bios Menu Screen

Page 64: menu items, page 65: main menu, page 66: sata 1~6, page 67: storage configuration, page 68: system information, page 69: advanced menu.

• Page 70 The following item appears only when you set the AI Overclocking item to [Manual]. CPU Frequency [xxx] Displays the frequency sent by the clock generator to the system bus and PCI bus. The value of this item is auto-detected by the BIOS. Use the <+> and <-> keys to adjust the CPU frequency.
• Page 71 Allows you to set the CPU VCore voltage. The values range from 0.8500V to 1.55V with a 0.00625V interval. Configuration options: [Auto] Setting a very high voltage may damage the component permanently, and setting a very low voltage may cause the system to become unstable. ASUS P5QL-EM 2-21...

Page 72: Cpu Configuration

• Page 73 ® ® [Enabled], you can adjust the system power settings in the operating system to use the EIST feature. Set this item to [Disabled] if you do not want to use the EIST. Configuration options: [Enabled] [Disabled] ASUS P5QL-EM 2-23...

Page 74: Chipset

• Page 75 96MB for playing and storing the decrypted contents. The operation system and other programs cannot use this reserved memory, and Vista Aero (DWM) is disabled. Feature PAVP Lite PAVP Paranoid Compressed video buffer is encrypted HW 128-bit AES decryption Protected memory (96MB reserved during boot) ASUS P5QL-EM 2-25...

Page 76: South Bridge Configuration

Page 77: onboard devices configuration, page 78: usb configuration, page 79: pci pnp, page 80: power menu, page 81: acpi 2.0 support.

• Page 82 Resume On PCIE Devices [Disabled] When set to [Enabled], this parameter allows you to wake the system through a PCI Express card. This feature requires an ATX power supply that provides at least 1A on the +5VSB lead. Configuration options: [Disabled] [Enabled] Resume On RTC Alarm [Disabled] Allows you to enable or disable RTC to generate a wake event.

Page 83: Hardware Monitor

Page 84: boot menu, page 85: boot settings configuration, page 86: security, page 87: change user password, page 88: tools menu, page 89: express gate, page 90: exit menu, page 91: chapter 3 software support, page 92: installing an operating system, page 93: drivers menu, page 94: utilities menu.

• Page 95 Installs the Ulead Burn. Now application for Audio DVD,CD and data disc creation. Ulead Photolmpact 12 SE Installs the Photolmpact image editing software. Asus Express Gate Installer Installs the ASUS Express Gate Installer. The screen display and utilities option may not be the same for different operating system versions. ASUS AI Nap...

Page 96: Manual Menu

Page 97: asus contact information, page 98: technical support form, page 99: asus express gate.

• Page 100 Select the target disk volume for you to install Express Gate. If you have multiple volumes and OS installed in your hard drive, it is recommended to install Express Gate in Volume C. Click Next to continue. Follow the screen instructions to complete installation.
• Page 101 Enter Boot selection pop-up In the Express Gate Environment: Function <Alt> + <Tab> Switch between softwares <Ctrl> + <Alt> + <Del> Bring up Power-Off dialog box <Ctrl> + <Alt> + <Print Screen> Save screen snapshot as picture to file ASUS P5QL-EM 3-11...
• Page 102 Using the Configuration Panel Use the configuration panel to change various Express Gate settings. Click on an icon to open a particular configuration tool. The following tools are available: Date and Time: set current date and time as well as time zone. •...
• Page 103 USB drive. If a USB device is detected, the icon contains a green arrow. ASUS Express Gate supports file uploading from SATA HDDs, ODDs and USB drive and downloading to USB drives only. Shows network status; click to configure network.
• Page 104 Click to choose input language and method as well as keyboard shortcuts (Ctrl-Space by default). Click to change LaunchBar options (auto-hide, docking position, etc). Click to show the “ASUS Utility” panel. Click to show “About Express Gate ”. Click to open Express Gate Help.
• Page 105 The most common scenario is for your computer to automatically obtain network settings (i.e. DHCP). If this is the case, you don’t need to click Setup for any LAN port. If this is not the case, click Setup to configure the static IP settings manually. ASUS P5QL-EM 3-15...
• Page 106 I m a g e control bar ASUS Express Gate supports HDDs connected to motherboard chipset- controlled onboard SATA ports only. All onboard extended SATA ports and external SATA ports are NOT supported. 3-16 Chapter 3: Software support...
• Page 107 Express Gate software will be released regularly, adding refinements or new applications. You can find original version of the software on the support DVD or download new versions from the ASUS support website. To update Express Gate Double-click the Express Gate setup file to start software update.
• Page 108 3-18 Chapter 3: Software support...
• Page 109 The Appendix describes the CPU features that the motherboard supports. CPU features...

Page 110: Appendix Cpu Features

• Page 111 On the Power schemes section, click , then select any option except Home/Office Desktop or Always On. Click Apply, then click OK ASUS P5QL-EM...

Page 112: Intel ® Hyper-Threading Technology

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