Okay, it's my turn now. Finished this build a week ago and ever since, it turns itself off after 3-12 hours of running. I monitor the temps and CPU/page file usage and everything is fine. I thought it was the cheap PSU and bought a Thermaltake instead but it still does the same thing. I ran the prime95 torture test and got the cpu temp from an idle 36 degrees to 51 degrees. And that's with arctic silver applied. It finished the first self-test fine and the machine never shutdown. Then I let memtest86 run 3 passes with no errors. Any ideas? Maybe the motherboard?