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.