IRQ settings - Help

[Generix]

I was looking through things today and ran across something that surprised me (see the attached picture). 7 different devices all mapped to IRQ 9?! I said to myself, "Okay, not a problem. I'll just change them to what I want." WRONG. Through investigation of the matter, I came across these Microsuck articles: One and Two. My motherboard does have Advanced Configuration and Power Interface (ACPI) on it, therefore I must reinstall Windows to "force the changes" set by Plug and Play. This is complete shit. I would sooner disable Plug and Play altogether. Oh, and this p.o.s. Gateway (Not my choice to purchase) has no helpful options in the BIOS what-so-ever for IRQ settings. The main problem I have with leaving these settings the way they are is that when I'm using my SCSI scanner, the internet disconnects and the whole system basically locks up until the scan is down (which takes forever considering that my scanner is a dinosaur) Is there any thing I can do? Any ideas? Any input on this matter is GREALTY appreciated. Thanks

-Generix

[Polariz]

In this support page below mate I found the following bit:

You cannot change the IRQ setting because the setting is unavailable. This occurs because Windows takes advantage of the ACPI features of the motherboard, including advanced PCI sharing. IRQ 9 is used by the PCI bus for IRQ steering. This feature lets you add more devices without generating IRQ conflicts.

General Description of IRQ Sharing in Windows 2000

Obviously MS shows this to be not a problem for this many devices to have the same IRQ (no.9), so this is a little strange. Could it possibly be a driver problem?

[Generix]

I don't see how it could be a driver problem. If I updated my drivers, they would still remain locked on to IRQ 9. By the way, I installed an ethernet card today because I needed it for my new DSL (HELL YES!!!!!!) and you can guess what IRQ it went to....yep, 9. *sigh* I'm thinking that there is no cure for this problem.......blah

[Polariz]

That's what im saying though, that support page says that them all going on 9 isnt a problem, and if that network card works then that probably proves it.

Treat yourself to a new scanner hehe.

[igalan]

Does your system suffer from instability? If not, then leave the IRQs as they are. Most modern hardware is able to share the IRQ, and with properly written drivers (this is the key) you won't suffer instability or much performance degrade (however there is some).

If you have problems, there are only three ways to change IRQ:

1.- If your m/b BIOS allows you to specify the IRQ for each PCI slot, then use this feature and set P&P OS to NO. My old Asus A7A266 allowed this, but my new Asus A7N8X Deluxe not (but there's no need because it uses APIC.)

2.- Changind a card to a different PCI slot will usually change also the IRQ. Of course this is not possible with integrated hardware.

3.- As a last resort there is a trick (that sometimes doesn't work, and can even make things worse):
Reserve IRQ 9 in Windows and restart. Since IRQ 9 is reserved, Windows will assign a new IRQ for all the devices that were using it. Most probably will assign all of them to the same IRQ (not 9). Now free IRQ 9 and restart. If you'r lucky only some devices will move again to IRQ 9, but that does not always happen.

[Generix]

My system is fairly stable....Only two lock ups in four months

[igalan]

Originally posted by Generix
My system is fairly stable....Only two lock ups in four months

If you're concerned about stability or performance then you may want to try the first and second method to reassign IRQs. But two lock ups in four months is quite good (of course depending on what you do with the computer ).
If the VGA has a separate IRQ this will improve performance and stability (only a little bit). Don't try the third method, is not worth the effort if everything is running well.

[Generix]

Okay, well as it stands now, I only have one free pci slot...the one next to the agp (which I don't want to block for heat reasons). Also, my lame gateway BIOS is no help what-so-ever. Thanks for the help though

[igalan]

Usually the IRQ of the AGP slot is shared with the PCI slot next to it, so don't loose your time changing a PCI card there... Sorry, but I don't know a way to reassign IRQ . However, as I said, if your system is stable leave it as it is now .

[Cirga]

In my experience.. when you attempt to change IRQ's you run into big trouble. Merely becuase each IRQ has a purpose.. and with windows IRQ steering if you by accident assign an IRQ to the wrong device and windows attempts to access that very device.. or install another device there is a good chacne you will have a crash and burn situation.

The fact that several devices are assigned to the same IRQ's is due to windows doing so.. not sure why you would want to change htem in this regard..

Is there a specific reason? You stated that your system performance is great and its stable?

[Polariz]

The main problem I have with leaving these settings the way they are is that when I'm using my SCSI scanner, the internet disconnects and the whole system basically locks up until the scan is down (which takes forever considering that my scanner is a dinosaur)

That's his main problem, he beleives that the IRQ's are causing the scanner to bugger up.