Another shutdown problem...

First of all I'd like to say thank you all in advance for reading my humble little post...but this one has me stumped

The problem I am having is that I cannot get completely through the boot process before my machine shuts down (as in like someone pulled the plug). Sometimes I can get to the windows loading screen and other times its within a few seconds of me pressing the power button (15-30 seconds), its seems random to me. I have tried replacing the power supply with a new one but it changed nothing. I have tried disconnecting everything but the bare essentials (additional HDDs, disc drives, etc) to run but still no changes. I recently moved halfway across the US (CT-MN) so there is a possibility that it was damaged during transit but its a little out of my range of expertise...

-specs-
CPU - Intel core i7
Mobo - Asus p6t6 WS revolution
Gfx - Nvidia 560 Ti
PSU - Kingwin LZ-100 or ThermalTake TR2-600
OS - Windows 7 Ultimate (64bit)

Thanks in advance for checking out my post and I look forward to hearing from you!!

 

I agree with plodr, this sounds like an overheating issue.

You can check this by disconnecting your hard drive and unseating your GPU and RAM. Boot the machine and let it run for about 2 minutes. You should hear the RAM beeps (RAM missing or faulty). If your PC shuts down in 10-15 seconds, then you would have narrowed the problem. Chances are it will be one of the following:
1 Dirty heat sink
2 Faulty heat sink fan
3 Old/Cracked thermal paste

 

Well, I removed the CPU fan and was appalled at the amount dust and just plain old gunk underneath it, I'm guessing its been loose for sometime now so I removed all the old paste, gave it a fresh application of new stuff, blasted the fan with some compressed air and everything seems to be working great now!! Except its trying to load XP instead of Windows 7. Thats a problem I've dealt with before so the hardware problem has been fixed thanks to you guys!! I am very appreciative of you help!!!!