Something about this board is bugging me, and I need some help. I have a setting for my Q6600 at 3.2GHz for low-power job, and that setting has been blessed by both Prime95 v25.6 small-FFT (15.5 hours) and Blend (12 hours). Still, I am suffering random system restarts from time to time, out of no reason at all. The BIOS version is 0314, which is also the same BIOS those rigorous long tests passed with.

Every time this happens I checked Windows Event Log and there's nothing wrong reported. It shows as if I restarted the system, while in fact the PC tripped itself. I even had the temperature warning disabled in the BIOS and that still doesn't stop this problem (so apparently it's not heat related). BTW during those Prime95 tests none of the core temps went beyond 57C at 3.2GHz.

I suspect I got a bad board, but if it is bad why it was so solid during those long burn-in sessions (I have Everest event logs back that up: all volts are nearly unmoved). The PC is plugged in to a 750VA UPS as well. What could be wrong when all the tests results are perfect? I need troubleshooting ideas...