So I start to make a new rig, I didnt bought everything I need more RAM and a GPU, but I decided to turn it on just to make sure everything was fine, but then it start shutting down for no reason, I had an old HDD with windoes 8 and it seem to work fine, but in windows 7 is making the system shut down sometimes without warning I had to Hard Reset my PSU everytime it happens if not my PC won't turn on again, my dad was about to play candy crush xD and it shut down, I played minecraft and nothing happend, I try to run speedtest.net and it shutdown, So i dont know what is causing the problem any help?
Specs
4gb RAM DDR3
Phenom ii 6x Black Edition 3.2ghz
Diablotek 600W
Aerocool X strike
Corsair H100i
Toshiba 1tb