At Power up immediately shuts off

[ja0056]

I have a PC that as soon as you touch the power button to turn it on it turns on and instantly shuts off. If you remove the processor and turn it on, it stays on. I've tried a new processor and get the same thing. I'm not sure where to go next.
Thanks in Advance.

[PrntRhd]

See this post for Sylvanders' Flow Charts for Troubleshooting. They are actually quite good. flowchart thread (http://www.pcguide.com/vb/showthread.php?s=&threadid=24421)

or direct link here (www.erniek.eclipse.co.uk/downloads/sylvanderdiags.zip)

[david eaton]

Also check the Processor heatsink and fan. The shutdown could be due to overheating.

[Paul Komski]

... and if not actual overheating - the mobo may shut the system down if it doesnt detect that the HSF is working to prevent overheating happening in the first place.