Installed GTX 680 - Computer crashes

Hi guys,
I recently installed a new GTX 680 Phantom and it worked great. After a couple of hours or even sometimes 20mins of playing a game; my computer would instantly shut itself down - no warning, no graphical glitches, just bam and its gone. I could restart the pc and it would act like nothing had happened but then do the same thing at a random time while playing.
I downloaded EVGA Precision to try and monitor the GPU and all the readings came back completely fine.

I assumed it wasn't the graphics card at this point and upped the power supply from 750W to 1050W thinking that the system as a whole was simply drawing too much. But this hasn't fixed the problem and now its having the same crash within 30 seconds of just loading into windows.
It works in safe mode and I've been able to uninstall the card and drivers but it wont let me reinstall the card in safe mode as the CD drive is out of action then and it wont stay alive long enough in normal mode to let me install it.

So the question is, what do I do?

A few specs:
CPU - Intel quad core2 Q9400
GPU - Gainward Geforce GTX 680 Phantom
PSU - 1050W
4 GB DDR2 ram
Win7 32bit