I have a gigabyte UD3r x58 mobo with i7 920 @ 3.66, voltage 1.2875. I did prime95 @ 3.8, same voltage, for 12 hours with no issues. However, on occasion it will fail to even reach bios stage of boot and the backup bios will kick in and tell me about this failure. I used to think failure to at least boot would not happen unless I pushed the system past windows stability. Any thoughts on what might be wrong?