Just thought I'd add that clearing CMOS didn't solve the problem. As for the motherboard and processor being defective and/or incompatible, I doubt it. I bought duplicates of the motherboard and processor and have the same problem. Before buying the first motherboard/processor combo I checked with the companies to make sure the board and CPU were compatible. The processor used is a Intel Pentium 4 631 and the motherboard is a ASUS P5P800-VM