Computer Randomly Freeze once in a while

Everything working fine temp wise or so i think (i attached a pic of my CPUID HW) But recently i experienced some computer freeze. The first time it happend is about 2 weeks ago and i had to do a restart since it just completely froze. And just now it happend again so i am just wondering what is the cause of this. The ram and PSU is pretty ****ty brand and i am running an i7 2600 and 6970

http://img12.imageshack.us/img12/4625/unlednb.png

Yeah you need to get some good memory and swap out the psu anyway as they are some pricey components you have at risk...

If the PSU is as bad as you say it is, then that's probably the problem. Give us the model number of it.

Sorry to bring this up but i just got back to work on this.

I did a memtest and it passed. What do you mean brand of Intel and W? It is an i7 2600 and the PSU isXON-700P12N. It crashed again today while i play League of Legend but i think it just random crash and not because the PSU cant handle the load since it never crash while i play The witcher 2 or Crysis 2. So what should i do next? should i swap out PSU and see how it goes?

and i do have the latest Video driver. Another thing i forgot to mention that i see some artificat such as green horizontal line in blac area on my screen while i tried to use eyefinity but i only had 2 screen at the time so i didnt think much of it. Is it possible that the GPU causing the lag?

I did Furmark and my GPU ran fine. I figured out that the artifact came from the monitor since it dissappear after i turn screen off then on. According to the event viewer, The problem is critical - kernel power - event id: 41. It happend 4 times total in 1 month span, 3 of those happen while my bro was playing league of legend and the last one happen while i was watching youtube in fullscreen mode. I played about 20 hours of the witcher 2 but not a single crash and no artifiact. I did a bios update, video update, virus scan, clean registry and some other stuff. Hopefully that'll help.

My spec:

I7 2600 - stock

diamond 6970 - stock

1tb hdd

8gb ram - i dont know which brand, does it matter?

700w xon - 700p12n

thanks for those but the answers are still very broad. What do you suggest i do first?