I built my computer back in 2010 and have been having freezing problems the day I put it together, mainly in games. Sometimes it doesn't freeze at all for hours on end and other days it will freeze within minutes a number of times, forcing me to power it off each time. Rarely, it will freeze while watching streams in HD or right when I open a new tab on my browser. It used to only freeze one time during games and never freeze for the rest of the day but lately it has been freezing multiple times.
Also, my computer hangs on boot up at a black screen and either restarts itself or forces me to restart it. One restart at boot up and it always boots perfectly after. The problem is not my GPU because I originally started with a gtx 460 and several months ago switched it out for a gtx 480 and the problem persisted. Memtest was also ran for roughly 24 hours and came back with zero errors. Heat is a non-issue as well because I monitor the cpu and gpu temps and they stay at fine levels. Lastly, after it freezes and boots up after I power it off I check the event viewer and there are no errors besides a critical error just stating that the computer powered off in an abnormal way.
Windows 7 64
phenom II x4 955 BE
Asus M4A87TD EVO.