but how is the BIOS set? "PNP/PCI Configurations"* is this set to "auto" or "manual"?
Setting it to "manual" will allow you allocate IRQ's.
*This my motherboard reference in advanced menu.
You could try resetting this and seeing if it makes any difference. Also, if you have onboard sound, you will probably know this, make sure EVERYTHING relating to onboard sound is disabled.
At least this will bump you to top again.