I recently just built a desktop and noticed that it would randomly turn off and reboot with no pattern to it. Sometimes happens a few times a day or none at all. Temperatures idle at the mid 30*C and reaches up to about low 40's when i game. I've been told that HWMonitor is pretty inaccurate but i notice that my +12v is at 8.1V which sorta worries me. Any help would be appreciated, thank you.
Try other CPU temp monitors, maybe even monitor your GPU temps (my GTX 465 when it had it's stock cooler would overheat and shutoff during hot weather).
Make sure all connections are nice a tight, and if you're worried about the PSU, get it tested (there are self-testers but you would have to buy them). Or try a known-working PSU, a 1000W PSU is way overkill for a system like this.
I downloaded Speedfan and kept an eye out for the temps but my GPU would just idle at 24 to 25. I also went back into my computer to check on the wires and everything it as tight as can be. I'm sending in my PSU for a RMA and hopefully that would solve my problem.