I've build up a new PC and it frezes up time to time.
The thing that sometimes it happens while playing or 3d modeling sometimes it gust happens. Even if I just turned it on and left as it is. Timing is also random sometimes it's 10-15 minutes, sometimes it's 2-3 hours.
I've installed sofrware that tracks temperature to a file and before freeze it's about 65° for both CPU and GPU.
The symptoms is that the image suddenly freezes, the sound turns to "bzzzzzz" and hdd light turns off.