Hi, below you can see the Interrupt Request Table - something that used to exist in all mobo manuals and actually I've never cared about it. Now I'd like to understand how to read it, when to use it, which devices need separate IRQ and which can share it. Explain it to me please.
Well, it's pretty straightforward.
Most PCI cards use some IRQs to operate, so they use a INT line. When INT is signaled, the driver "catches" the interruption and do some things.
Well, not really. A good written driver catches the interruption, then checks if the device is generating the interruption and then do some things. If the device is not generating the interruption, it must pass the interruption to the next driver.
In the case above, AGP and PCI slot are using the same INT (INT-A). So, if INT-A is generated one of the driver must catch the interrupt (AGP, for example) and if his device is not using the interrupt pass it to another driver (in this case, PCI slot 1).
If the driver is badly written, the AGP driver may do some nasty things to the AGP card (which is unprepared, because it didn't throw the INT), and PCI slot 1 would never work as intended (because PCI slot 1 driver would miss INT-A).
If that would be the case, you would move PCI card from slot 1 to another slot, so it won't share IRQ with the offending card (or get a better written driver).
So this table is only useful if you have driver problems with your computer. In this case, PCI slot 2 would grant a working card (because it DON'T share IRQ) and, if you have an external audio card, you may disable onboard audio and free INT-C to grant another working slot.
I have traveled across the universe and through the years to find Her.
Sometimes going all the way is just a start...
The second trouble is - performance. If you have two devices on the same IRQ - you have speed loss.
He he, nice board. USB controller sharing with two pci slots. Trouble...
Thanks guys for the clarifying. So if I want to use onboard USB controller, I should avoid using pci slot 4 and 5, or else I _might_ get conflicts / performance losses?
Kind of, if you can avoid it avoid it, otherwise be aware of it having potential to be a problem.
For example a sound card shouldn't be on the same interrupt (but a sound card should be on slot 2 or 3 (and the onboard sound disabled in the bios).
