Hi guys, sorry for my first post here to be asking for assistance, im a long time lurker so I hope you will forgive me!

I built myself a new rig a couple of weeks ago, specs are:

i7 920
6GB GSkill 1333MHz DDR3
Gigabyte X58-UD3R-SLI mobo
2x 150GB WD Raptors RAID0
2x GTX 280 SLI
OCZ 900W Modular PSU

Basically, i was playing Left4Dead, and on several occasions after about 20-30 mins my system froze up. Complete lock, I couldnt ctrl-alt-del and the sound was looping. After a few seconds the video shut off and I was left with a black screen. This happened in DiRT aswell.

First things first, I thought it was my overclock I had applied (who here has a stock CPU? ), so I set the system to stock speeds on the GFX and CPU/mem, but hte problem still occurred.

I thought it might be the PSU at fault, but I dont want to spend lots of money on a replacement PSU (I don't have any spare ones that are powerful enough), so I thought of another stress test to perform. I ran the crysis warhead benchmark on a loop at 1920x1200 with 16x AA, with Prime95 blend in the background (8 threads), so I was stressing my system to the max. I ran 50 loops of the test, 1.5+ hours, and it STILL didn't crash, so i'm completely stumped as to the problem. I also tried updating nVidia drivers but it's still happening

If anyone has any suggestions PLEASE tell me, any information is greatly appreciated as im completely stuck

Regards
Ben (SBB)