Unknown hardware problem please help

[dave675]

I built a custom pc last year and it never worked great but has now become intolerable. It will randomly freeze up and never recover or it will bluescreen. It commonly happens when I what videos online such as youtube, sometimes even just adjusting from 480 to 720p will freeze it. Also when I am playing games it will freeze. Sometimes if I leave it on with nothing running just sitting on the desktop when I get back an hour later it will be frozen. I used windows memory diagnostic to test the ram and it came back with no errors. Use speedfan to view heat levels but they seem normal when it freezes. 3dmark to test the graphics card and it seems to of returned normal results. I used prime95 to test and on blend mode it froze up once and blue screened another time. P.S. Not overclocked.
Please help me figure out the problem I'm new to this and don't have parts to just 'switch out'
part list:
CPU: AMD FX-8350
MB: asrock 990fx extreme4
Graphics card: EVGA GeForce GTX 650 Ti BOOST
Ram: 2x kingston HyperX 4GB DDR3-1600
PSU: Cooler Master i600 - 600W
also 1tb hdd and a wireless internet pci card
Windows 8.1

 

[GhislainG]

All those components work without a PSU?

 

[dave675]

I didn't get a new motherboard, if i mentioned one it was a typo on my part.

Will update original post about PSU when i find the specifics again but im pretty sure it was ---
Edit: Cooler Master i600 - 600W