Newly built PC shutting down on bootup

The heatsink is totally seated, and you are confident that nothing is overheating?

I'm not confident nothing is overheating. Actually it seems to me that given the way it shuts down more quickly if I turn it right back on, it seems it would be a heat problem. The heatsink on the bottom of the CPU fan seems to be in properly. It doesn't move and isn't loose. And the fan is spinning fine. Can I remove the fan and run it without it if the case is open?

Also, the instructions on the fan were minimal at best. Do I need to apply anything to the heatsink before I set it on the CPU?

No, that wouldn't be wise .

Try leaving the side of the case off, grab a standard house fan put it a few feet away from the case on high. See if it stays on for a tad longer.

It'd probably either be your CPU, VPU, PSU or chipset overheating. You can take the VPU out of the PC to eliminate that. If your PSU's fan is spinning (turn the PC on and look inside/feel around the rear vent) then it's likely not that.

*Edit*

Yes, as I suggested above. You need thermal compound between the heatsink/CPU. If you have not applied this, do not attempt to start your PC again and apply the compound .

I just removed the cpu fan, pulled the cpu, cleaned both and replaced them, turning the heat sink 1/4 turn when I replaced it. When I turned it on the first time it ran for 2 minutes. I turned it back on and it ran for 53 seconds, but did shut down both times. I don't have the hard drive or a keyboard hooked up at this point but that shouldn't matter just to see it run, should it?

Just read your comment about the thermal compound. Where do I get it and what is it called? Is it just called thermal compound?

Okay, and you are applying thermal compound right (maybe the red will make it stand out this time )?

The boot process will hang if you haven't got an HDD installed and you might recieve an error/pause if you don't have a keyboard attached but the system will not shut off.

*Edit*

Sorry about that, posted while you did. Yes, you can just search any online outlet for thermal compound. Here is some Arctic Silver 5 from Newegg:

http://www.newegg.com/Product/Product.aspx?Item=N82E16835100007

Leave your system off until you have this applied. You need approximately 1 dot, between the sizes of a grain of rice and a small pea on the center of your CPU's heat-spreader. Then just sit the heatsink right on top as you probably have been without it.

Just looked it up, found it at Radio Shack nearby. Thanks for your help, I really appreciate it.

No problem. That is pretty much guaranteed to solve your issues. Good luck and post back with your results.

Thermal compound (also known as thermal grease) is used to transfer heat from the die of the CPU to the CPU cooler. Without it, there is very little transfer of heat. It is extremely likely that since you did not properly apply thermal grease, your system is shutting itself down in order to avoid CPU burn out. You are lucky. Many CPUs will just simply burn out and you are out several hundred dollars.

That's already been established Tedster .

Zenosincks, just wanted to add a quick note and say it now works fine since using the thermal compound. Live and learn. Thanks for the input, it helped tremendously.

Good news! Live and learn indeed, and you're more than welcome.