I've been getting random restarts lately. I dealt with some overheating issues about 4 months or so ago where my CPU was idling at 45-55c. I finally realized the CPU fan wasn't seated properly. Put on some thermal paste, got a new fan, and idle temps usually sit around 25-29c now.
I was playing Warhammer II a few weeks back and out of nowhere, my comp just restarted. I figured it was some sort of graphical glitch/error, no biggie. Then, it happened a few more times, during longer Warhammer II sessions. Because I can play World of Warships for hours just fine, I assumed it was just a WH2 issue and shrugged it off. So, last night I was playing Atlas with a buddy and my comp was restarting every 20-60 minutes. Immediately I go into BIOS to check temps and it really isn't too bad (40c-44c), considering it was just under load.
At this point, I'm starting to suspect a possible RAM or PSU issue, but the odd thing is that it's perfectly fine playing World of Warships. I've literally logged a 9 hour WoWS session, playing in fullscreen windowed mode and doing random shit on the internet at the same time (YouTube, websites, etc). I did check GPU temps as well and those are also in the 38-45c range after restarts (which, again, isn't too crazy considering it was just under load).
Not really sure what else could be the culprit.