|I'm not trying to troll in here, but I recently had a similar experience with a system build. Turned out to be the 3-month old PSU from Thermaltake. RMA, never crashed again. I'd strongly recommend that before you play too much.|
For what it's worth, my situation was quite similar. Computer would run fine for 8-10 hours, sometimes a day or two. Then would shut off. A few minutes later I could restart it, and it'd run for another couple of days. I ended up replacing the machine since the mobo and processor were 4 years old. Long story short, I tried to use the PSU in a different build, and wouldn't run, so I called Thermaltake and got a replacement unit, and never had another problem. I even rebuilt the old PC, and it's still running great too.