Computer Crashing

So ive had my computer for about 7 months now and all the sudden it has been crashing after about an hour of use. im going to post the specs of my comp.

MOBO: GA-990FXA-UD5
CPU: AMD Phenom(tm) II x4 965 Processor
GPU: Geforce 560ti
Ram 16gig 1600 Vengeance
PSU: 1000watt Coolermaster
SSD: hitachi 64gig
HDD: Not Sure just hold my games about 500gig

I noticed the crashing first when i was playing Diablo3 now when i just use my computer for browsing or whatever. it will crash restart but freeze on the screen that tell you what to hit to enter your BIOS. Ive been having this problem for about 5 days now and i have no idea what it is.

Ive Put in a new video card did same thing. I bought all new ram still did same thing. i ran the temp on all my stuff and its not running hot at all. all the fans work and my computer is super clean. My buddy said it could possibly be my MOBO but its so new i dont wanna believe it and i dont feel like doing the work.. But i will if thats what it is for sure.

 

more likely PSU

 

I agree, its usually the power supply that's the weakest link.