Custom Built PC shuts down while playing High end games or after a while.

[xmorbidartx]

(Apologies for double post)

Hey there guys, ill get right into it. I recently bought a few pieces of hardware to build a custom computer.
The specs are:

Motherboard: EVGA Nforce 750i SLI FTW supporting socket 775.
CPU: Intel Core 2 Quad Q8400 Bx 2.66 GHz@1333 4MB cache.
Video Card: EVGA Geforce GTX 280 1gb DDR3.
Power Supply:  Apevia 680W Iceberg Power ATX 12V complaint, sli ready.
Memory: 4 sticks of Corsair XMS2 2GB ddr2 pc 8500 1066MHz. (my motherboard supports a total of 8 GB)
Harddrive: My old hardrive, MAxtor I believe of about 80 gb of space (yes pretty low).
Case: HAF 932 Cooler Master Full tower chassis.
OS: Legal Windows XP 64x.

Haven't overclocked anything, grounded myself and made sure to be extra careful with the hardware while installing. Have new, clean case and my system boots up fine and will be on for a while. It is when I begin to play video games such as perhaps Race car GRID, CoA or WoW that my computer will randomly shutdown. Something to note, when installing, I transferred my old Hard drive from my previous custom built PC, I did not reinstall a clean version of windows, jsut stuck with what I had. The OS booted up and I used the CD to change up a few things like the ethernet drivers, that's about it. With that in mind, would anyone have any idea of why my system seems to be shutting down on me? It's pretty obvious it may be an overheating problem, but ive even tried using a huge fan I have in my room to see if it would provide efficient cooling, just wouldnt do it.

If anyone has any tips or ideas let me know, and ask any other questions if I didnt cover everything.

[Calum]

Sounds definitely like an overheating issue, use Speedfan to monitor your temperatures.
Most likely culprit is your CPU heatsink - reseat it, cleaning off the old thermal paste and applying some new paste per the manufacturer's instructions.

Also, you'd be much better to do a fresh install of Windows - I don't think that would be causing your shutdown issues, but you may find problems later on.

[squall_01]

I mentioned that  I think post start too look the same.

[Calum]

Sorry ... didn't realise it was a double post, my mistake.

[squall_01]

A little surprised but that it is.

[neelchauhan]

Try these:
1. Try placing your PC in a very cool spot.
2. Add a Exaust Fan
3. Add a Third Party CPU cooler