Might Be A PSU Issue, but then again may not

[wellies]

Hi everyone, first post on here hopefully many more to follow.

Ive just finished building a computer and everything seems to be fine, however after about 1 and a half hours it randomly restarts (regardless of usage). Its not overheating as i have so many fans in there it could take off and its never gone above 35C. But people are saying it could be the power supply. Here is my system

Processor:Intel Core i7-920 Socket 1366
Mobo:Asus P6T Deluxe Intel x58 Socket
Ram:OCZ 6GB DDR3 (3x2GB)
HDD: Seagate Barracuda SATA2 500GB
GPU:GeForce 9400 512MB DDR2
PSU:Cooler Master Real Power 620W

Is it a powersupply issue or a compatability issue, or something else?

Any help will be appreciated, or if you need to know anything more please ask.

cheers guys

 

[johnb35]

Have you looked at the event viewer for possible information what it could be?

 

[jbell1993]

I Had this problem with my old PC, and it turned out it was my PSU i was trying to run too much and after about 1-2 Hours It would shut down, if you can try a another power supply of a friend or something maybe just to make sure that would probably be the best option to see if it is the PSU