I built a computer about two years ago and it's been working great up until last week when it started shutting off randomly. It doesn't give any error messages, no bsod, nothing; it's as if I had ripped the power cord out of the computer. Sometimes I can leave the computer on for a whole day without it happening; sometimes it happens four times in an hour (though it seems to happen more frequently when I'm playing computer games).
My first thought was that this was a heat issue, so I enabled logging on Core Temp and found that the temp was 67 deg Celsius before it shut off. That sounds hot, but not hot enough to cause the computer to crash.
Since its not cpu temperature, I assume its one of the following things, but I have no idea which is most likely or even how to narrow down the list:
1) PSU is going bad
2) Mobo is going bad
3) Graphics card is overheating
4) Ram is going bad
Is this list accurate, and how do I test for each of these things?