I have an 845 based board and let me share that the current design does NOT require spare IRQs, but the current direction is to do IRQ sharing. I only see an issue if someone tries to control the IRQs themselves.
Be sure the BIOS is current, that you've reset the CMOS confifuration data and avoid the slot next to the AGP slot and it works.
Of course, if you try to assign IRQs on your own, then that's your wrestling match. I can't help you.
I am having a somewhat strange memory range resource issue with my modem. This same situation has surfaced before when I installed a new SB Audigy2, but after a few reinstalls, changing of PCI slots and some loud obscenities, the problem seemed to fix itself and everything worked out fine. Now, after an unrelated issue forced me to reinstall Windows (my luck just really sucks) here comes same problem again. Only this time, it's not going away. Removing and replacing the modem (using the Windows auto hardware install) still gives me that nasty yellow exclimaion mark. Then when I try to reinstall the modem from scratch (using the software CD), I'm informed that I don't have any free IRQ's. I thoght maybe the modem was installed multiple times, but I see it only once in Device Manager. Even removing the device, drivers and programs entirely don't change a thing. Nothing appears in the Conflicing Devices list of the modem properties though there are conflicts in the Memory Resources list but I'll have to get back to you on what they are since I'm not at my computer right now. I do remember that they are system devices. I did the same procedures with the sound card, since that's when the problem first started, but still no dice. Removing the sound card does remove the yellow exclimation, but the modem still fails to work and still gives me the insufficient IRQ error when reinstalling. I'm pretty sure there's something I'm not seeing as this problem was fixed once. I just don't know how. Any help would be greatly appreciated.
MSI 845GE Max Mobo with P4 2.4 Ghz
Windows ME (Yeah, I know)
U.S Robotics 56k Modem