Pc Keeps shutting down!

[ohwoojin]

Hey everyone,
Had my computer a while now. Was great until recently its started shutting down randomly. Have no idea why. I built the system and thought everything was stable but now not so sure. I know it could be down to a few things but have no idea how to find out which one it is? Any suggestions?
Cheers!

 

[ohwoojin]

Made it last year in March. lol. Its not that obvious. just opened the case and everything seems fine. Cpu fan is doin nicely temps average at 49. So dont think its the processor. Unless i havent got the voltages right.....

Wasnt sure if its the PSU. I bought an good quality one so didnt think it was that. but am not sure how to go about checking.

I really have no idea what to do or check....