Shuttle AK35GTR - How are IRQs shared?

[MichaelD]

Hi there,

My server uses a Shuttle AK35GTR; stable as a rock, not a prob in years.

I'm rebuilding it and I'm adding a SCSI card. The OS will be on this card. I want to be SURE the PCI slot the card is in isn't sharing an IRQ w/anything.

I know that typically, AGP and PCI 1 share an IRQ...other than that, I'm clueless.

Can you help, please?

 

[MichaelD]

Bah. I didn't think anyone still ran this mobo. Guess I was right/

 

[MichaelD]

I have checked out about three dozen pages on the net; can't find anything!

 

[Zap]

Couple of ideas...

When the machine POSTS, right before loading the operating system the BIOS will list all PCI devices and which IRQ they are on. You can play around with using that to find out the best slot.

The BIOS may also report the IRQ allocation within it. Go to the screen that lets you manually set the IRQ and see if it reports which PCI slot the setting is for (slot 1 is nearest AGP).

Traditionally a board can allocate 4 IRQs to PCI devices. The AGP counts as a PCI device, so that shares with the first PCI slot next to it. USB usually shares with slot 4. On a 5 slot board, #5 usually shares with #4. On a 6 slot board (like yours) #5 and #6 can get mapped both to #4, or to #4 and #3. Onboard RAID usually maps to #3. Thus, your best bet would be to pop the card into slot #2 (second from the AGP).

Of course if you have a more modern PnP operating system like Windows 2000 or Windows XP, don't worry about it since Windows seems to ignore hardware IRQs. Only in the older Windows versions does it become an issue. On older systems, some cards will share and some will not. The PCI specification allows for sharing, however the card has to be manufacturered to allow it also, plus the device drivers have to be written to support sharing as well.

Devices that usually allows for sharing are:
- video cards
- network cards
- port cards (USB, Firewire)
- HDD cards (SCSI, IDE)

Devices that usually don't like sharing (though they may be able to) are:
- modems
- sound cards

 

[thermostat]

I am running that motherboard also it is a darn good one! Plus I have SCSI card in it that runs just fine. I am using win2000 and it manages all the IRQ's with no problem. However if you insist fo ino the bios and you can reserve an IRQ for a PCI slot. Or SHuttle is very good about answering technical questions, just email them.