IRQ Sharing

CyNics

Senior member
Dec 28, 2001
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I have this weird problem since the first day I bought my EPOX 8KHA+. If I install w2k on it, all my PCI cards, graphics, USB will share one IRQ, IRQ9. But if I install WinXP on it, all my PCI cards, graphics card and USB will have their own IRQ. Same BIOS setting(PnP = OFF, ACPI = enable). So I did some searching and I found these:

Microsoft Knowledge Base Article (Q314068) - Manually assigning IRQs to PCI slots in the system BIOS as a troubleshooting method may work on some non-ACPI systems that use a standard PC hardware abstraction layer (HAL), but these settings are ignored by Plug and Play in Windows if ACPI support is enabled. If you need to manually assign IRQ addresses through the BIOS to a device on an ACPI motherboard, you must reinstall Windows to force the installation to use a Standard PC HAL

So microsoft says that manually assigning IRQs to PCI slots in the system BIOS will be ignored by plug and play in windows if acpi support is enable. BUT that only happens if i install w2k, it doesn't happen if I install winxp cause I tried before, all my PCI cards, graphics card and USB had thier own IRQ in winxp (i assigned for them in the BIOS)

Mushkin_Rules (Amdmb.com Forums) - If you fresh install Win XP with ACPI ENABLED, make sure that in bios menu (page 4-17 in manual), in "Power Management Setup" , the "ACPI Function" is set to Enabled. Unlike my Asus A7V133 and Iwill KK266-R (VIA KT133A chipsets) that automatically set IRQ to 9 (sharing with ACPI function) when installing Windows 2000 or Win XP (by default) with ACPI Enabled, this Epox 8KHA+ (also with Soyo Dragon Plus or any other VIA KT266A chipsets mobo) automatically set IRQ to its own IRQ settings that have been set in bios menu. This is nice features, as IRQs are no longer shared !!! I suggest you fresh install Win XP by default setting, with ACPI Enabled.

Mushking_Rules (Amdmb.com Forums) - * IF YOU FRESH INSTALL WINDOWS 98/98SE/ME/2000/XP, BY DEFAULT IT WILL INSTALL WITH ACPI ENABLED

* IF YOU DO NOT WANT TO USE ACPI, BEFORE FRESH INSTALLING WINDOWS, DISABLE ACPI IN "POWER MANAGEMENT" IN BIOS MENU. WINDOWS WILL BE INSTALLED WITH STANDARD PC

* IF YOU FRESH INSTALL WINDOWS 2000 BY DEFAULT WITH ACPI ENABLED, ALL PCI & AGP CARDS WILL BE ASSIGNED TO SHARE INTO ONE IRQ, EITHER IRQ 9, OR 7, OR 11 -> why it only happens to W2k and not winXP?

* IF YOU FRESH INSTALL WINDOWS 98/98SE/XP, PCI & AGP CARDS WILL NOT BE SHARED INTO ONE IRQ. HOWEVER, IN WIN XP, ACPI WILL OCCUPY IRQ 9 BY DEFAULT. ANYTHING ASSIGNED TO IRQ 9 IN BIOS MENU WILL BE ASSIGNED BY WIN XP TO THE NEXT FREE IRQ, BECAUSE IRQ 9 IS BEING USED BY ACPI -> see that?

W2k and WinXP are similar in many ways (NT Kernal). So can anyone explain to me why is w2k ACPI acting so weird(or maybe winxp)? Does it depends on what motherboard do you use because Mushkin_Rules did mention about it (If you fresh install Win XP with ACPI ENABLED, make sure that in bios menu (page 4-17 in manual), in "Power Management Setup" , the "ACPI Function" is set to Enabled. Unlike my Asus A7V133 and Iwill KK266-R (VIA KT133A chipsets) that automatically set IRQ to 9 (sharing with ACPI function) when installing Windows 2000 or Win XP (by default) with ACPI Enabled, this Epox 8KHA+ (also with Soyo Dragon Plus or any other VIA KT266A chipsets mobo) automatically set IRQ to its own IRQ settings that have been set in bios menu). But then microsoft says that manually assigning IRQs to PCI slots in the system BIOS will be ignored by plug and play in windows if acpi support is enable??? :confused: :confused: I want to switch back to w2k because I like it more than winXP but my audigy will have some skipping problems if some other devices share the same IRQ with it.
 

Proxius

Junior Member
Sep 25, 2002
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0
Yeah, I was wondering about this too.

Which way is better in XP?

Let ACPI handle it, or go to "STandard mode" and
let the BIOS assign them...any thoughts?
 

CyNics

Senior member
Dec 28, 2001
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86
Originally posted by: AndyHui
Please read the FAQs:

Why are all my devices using one IRQ in Win2K/WinXP?

ACPI vs APM

Andy, "why are all my devices using one IRQ in Win2k/WinXP" isn't my question and I do know that it's normal for all devices to share one IRQ in Win2k/WinXP. My main question is "why all my devices share one IRQ in W2k but NOT IN WinXP" and since both of them are similar in many ways, why it's only happen in W2k and not in WinXP
 

Proxius

Junior Member
Sep 25, 2002
2
0
0
Thanks Andy!

Thats is good info on ACPI. For some reason when Installing XP my SOYO dragon plus doesn't let me use ACPI. I want to try it and see if my problems go away.
I will update the BIOS tonight (it's never been updated) and see if XP will go into ACPI mode then.

Thanks again!
 

CyNics

Senior member
Dec 28, 2001
270
0
86
Yeah Anandtech's FAQ is a good place to look for answers :)

WinXP let me use ACPI but it's doesn't make all my devices to share one IRQ. It's totally diff. in w2k. W2k let me use ACPI too and it makes all my devices share one IRQ.