Vid Card/Sound Card IRQ Sharing: Is This A Problem?

[Mulsiphix]

I am reading a Windows tweaking guide which covers the possible performance drop, in major peripherals, shared IRQ's can cause. I checked and see that my X-Fi shares the same IRQ with my 8800GTX. Physically (mobo slot placement) the graphics card and sound card are as far apart as possible. I could shift the X-Fi to a PCI slot that is closer to the 8800GTX but I'm not sure if that would change its IRQ assignment. Seeing as all I use this computer for is gaming should I be worried?



ADDITIONAL RESEARCH
If IRQ sharing is a problem here is some additional research I have done. If it isn't please ignore the following.

Frustrating IRQ Assignment
I can see there are devices which shouldn't even get IRQ assignment as they aren't used which is very frustrating:

1. (ISA) 09: SCSI/RAID Host Controller
2. (ISA) 14: Primary IDE Channel
3. (PCI) 16: Creative SB X-Fi
4. (PCI) 16: NVIDIA GeForce 8800 GTX
5. (PCI) 17: Silicon Image SiI 3531 SATA Controller
6. (PCI) 21: Standard Dual Channel PCI IDE Controller
7. (PCI) 22: Standard Dual Channel PCI IDE Controller

I use a single IDE for my DVD burner, the secondary IDE channel is disabled, I don't use a RAID configuration, any SCSI devices, and my HD's are SATA. So why are list entries 1, 6, & 7 allocated IRQ's?

Noway To Reassign That I Know Of
In device manager I checked the properties for the X-Fi and 8800GTX and manual adjustment of the IRQ's was disabled. In my BIOS only certain IRQ numbers are adjustable and 16 is not one of them. There is another part of my BIOS that allows manual IRQ number assignment for each of the PCI ports on the motherboard. The settings are AUTO, 5, 7, 10, & 11. How the X-Fi in PCI Port 3 is assigned to 16 I don't know. I wasn't sure if it would cause problems to manually assign an IRQ for PCI Port 3. Any advice?



A Possible Solution Has Been Found
After thinking about it I remembered that Daemon-Toolz mentioned its need for the SCSI/RAID driver during its installation. SO I uninstalled the program and the SCSI/RAID Host Controller entry disappeared from the list and was replaced by Microsoft ACPI-Compliant System. After rebooting my system the X-Fi moved to IRQ 19. The X-Fi has IRQ 19 all to itself and the 8800GTX shares its IRQ with the Silicon Image SiI 3531 SATA Controller. Now my only question is am I at any kind of performance disadvantage because the X-Fi is now farther back in the IRQ list?

Dead End Reached For Virtual Drive Software
Just installed Alcohol and it installed the same SCSI/RAID Host Controller as Daemon. So I tried SlySoft's Virtual CloneDrive and it did the same thing. It appears as if these SCSI/RAID Host Controller drivers force the X-Fi and 8800GTX to be together.

When these drivers are installed no actual IRQ changes. Without a program like Alcohol 120% or Daemon-Toolz IRQ 9 is labeled Microsoft ACPI-Compliant System. When they are installed Microsoft ACPI-Compliant System is not listed and IRQ 9 now reads SCSI/RAID Host Controller.

The Final Questions
Seeing as I enjoy the convenience of virtual drive software I prefer to just deal with the SCSI/RAID Host Controller and IRQ sharing. So is there a risk of performance loss with my sound card and video card sharing the same IRQ? I would imagine there would be in sound/graphic intensive gaming sessions but am just not sure if it is worth worrying about. Please advise

[Adrian Wong]

Why don't you just enable APIC in your BIOS? Check it out here - http://www.techarp.com/showFreeBOG.a...ng=0&bogno=363

[Mulsiphix]

ACPI and IOACPI are both enabled in the BIOS.

[Mulsiphix]

The Microsoft APIC-Compliant System and the SCSI/RAID Host Controller are now sharing IRQ 9. I tried disabling the Silicon Image SiI 3531 SATA Controller (E-SATA) and one of my two NVIDIA nForce 430/410 Serial ATA Controller (SATA) but all it succeeded in doing was pushing my X-Fi and 8800GTX back to IRQ 19. No matter what, so far in my testing, when the SCSI/RAID Host Controller is installed by virtual drive software my X-Fi and 8800GTX are forced to share an IRQ. I just don't get it.

[Adrian Wong]

Originally Posted by Mulsiphix

ACPI and IOACPI are both enabled in the BIOS.

APIC is not the same as ACPI.

Check out the link I gave you.

[Mulsiphix]

Alright I have an IOAPIC function. Is this the same thing? I disabled it, saved the settings, and my system rebooted it. I immediately went back into the BIOS to make sure it was still enabled and it was. I booted into windows and nothing had changed. I rebooted, went back into the BIOS, and this feature was enabled. I went through this cycle a few times and it seems as if the function auto-enables itself when I boot into Windows. Any suggestions?

[Adrian Wong]

No-no.. You should ENABLE it. If you have enabled it, I don't think you need to worry about IRQs. It enables a whole lot of IRQs for your system to use.

If you are using a relatively new operating system like Windows XP and Windows Vista, the system will automatically share and switch IRQs whenever it needs to. So, you don't really need to worry even if Device Manager states the devices are sharing IRQs.

Just as long as you enable APIC and ACPI, and set the BIOS to automatically manage the IRQs, you will be alright. You might want to disable PnP too. Check the BIOS Optimization Guide for more details.

[Mulsiphix]

Many thanks for your help

[Adrian Wong]

Originally Posted by Mulsiphix

Many thanks for your help

No problem.