Am going from memory but was just looking at the resources of a similar Asrock soc 775 board a few days ago, over the weekend. Does it show ACPI with an IRQ ? (Dev Manager, view by resource iirc)
Mine (ACPI) was at 9 and showed all the SATA, USB, etc all at IRQ 16 and up. Most of the other typical board stuff was at standard IRQ's with 3, 4, 5 and 7 open (have the com and lpt disabled) and PCI audio card....
Am going from memory but am fairly sure is what I saw...added: Ohh but think it is running Win ME, cannot check until next weekend.

ACPI is taking IRQ 9. It's an old 98 SE installation, I currently install 9x without ACPI to reclaim this IRQ.

But here the problem are the 4 USB controllers built into the ICH5. I can't change their resources via Device Manager, Windows allows only the "default configuration". They happily share IRQ 10 and 11 with PCI cards, but IRQ 5, which I want for SB emulation is taken by one of them. And if I try to set the SB16 Emulation driver to IRQ 5, Windows will tell me I have a conflict.

The odd thing is, the driver seems to still use IRQ 5, just not in Device Manager. But I'm not sure what the implications of such configuration are. I want the USB ports for joysticks or wheels, so I can't just disable them.

Probably because of the on-board USB 2.0 controller. Those often take up three IRQs.

Check if your BIOS has an option to reserve IRQs for legacy cards, and turn that setting on for IRQ 5.

Joseph_Joestar wrote on 2023-03-22, 22:58:

Probably because of the on-board USB 2.0 controller. Those often take up three IRQs.

Check if your BIOS has an option to reserve IRQs for legacy cards, and turn that setting on for IRQ 5.

Unfortunately there are no settings to reserve IRQs on this board. I’ve seen such settings on other Intel 865 based board, but unfortunately not here. And I haven’t found any BIOS mods, probably because it’s one of these AMI bioses.

Hmm odd it assigns an 8 bit ISA IRQ to one of the USB. Would assume it assigned 10 and up (or should, as PCI IRQ's)
In bios do you have USB KB enabled or some such thing ? All I can think of is one USB has to be below 9 in order to support USB KB for internal use of BIOS if you want to use a USB KB in BIOS (edit: think it is USB legacy ??).
Ok am just guessing and am out of ideas other than it could be a AMI BIOS bug....

Have you tried disabling the USB ports in the BIOS, then letting the SB16 emulation take IRQ 5, and then re-enabling the USB ports? This musical chairs of IRQ's has worked for me on 2 systems now.

I have a very similar issue with IRQs as you with my ASRock QC6000M motherboard.

I can't get DOS sound working at all, although sound is working just fine from within windows.

Horun wrote on 2023-03-22, 23:34:

Hmm odd it assigns an 8 bit ISA IRQ to one of the USB. Would assume it assigned 10 and up (or should, as PCI IRQ's)
In bios do you have USB KB enabled or some such thing ? All I can think of is one USB has to be below 9 in order to support USB KB for internal use of BIOS if you want to use a USB KB in BIOS (edit: think it is USB legacy ??).
Ok am just guessing and am out of ideas other than it could be a AMI BIOS bug....

Legacy USB is Disabled. Enabling USB 2.0 changes nothing. It's either USB enabled and uses 3 IRQs for four controllers, or USB disabled and uses nothing.

mrzmaster wrote on 2023-03-22, 23:53:

Have you tried disabling the USB ports in the BIOS, then letting the SB16 emulation take IRQ 5, and then re-enabling the USB ports? This musical chairs of IRQ's has worked for me on 2 systems now.

If I let windows "automatically" choose the configuration, it will always choose the one without any IRQ (with IRQ 5 still working for some reason) (configuration 0003). Maybe there's some documentation on how Windows chooses the configuration for "automatic"? I was hoping it will choose "0000" if it sees, that IRQ5 is free (technically the IRQ Holder for PCI Steering is also getting IRQ 5, but my understanding is it doesn't matter, since this is just a "placeholder").

If I disable all USB in BIOS, force the "0000" configuration with IRQ5 and enable USB, Windows will show all of them happily sharing IRQ5, so hopefully it doesn't matter.

One additional scenario. If I reserve IRQ 5 in Windows, Windows will fail during booting if USB is enabled in BIOS. So, for some reason, one of the four ICH5 built-in USB controllers requires IRQ5 on this board.