I have a Tyan S7025 motherboard with 4 PCI-e x16 slot filled with four NVIIA Host Interface Cards (HIC). If I connect 0,1,2 or 3 of the HIC, a fresh install of HPC runs fine. When I connect the fourth HIC, the system slows by a factor of 5. I suspect an IRQ conflict. Is there a way to manually set IRQs in Windows 2008?
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I am assuming you mean Server 2008, With most devices you can't change them. And Windows does a good job sharing IRQs, so poke around in your Event Viewer to see if something else is causing problems