Computer Switch Off After Startup

Hi There,

I'm currently building a computer for someone and have done this lots of times before without error. However, i'm struggling with my current system at the moment.

Basically, when I switch the system on, I get the motherboard details on the screen, a ram check and the usual. But then suddenly it switches off. I have tried replacing the motherboard manufacturer, the power supply and removing PCI cards to no avial. I'm going mad!! What could be wrong??

It is a 3.0ghz LGA775 P4 processor, with a gigabyte motherboard and 1gb of Crucial ddr2 memory. I also have an ATI PCI-Express card and a SATA2 hard drive installed.

Any help on this would be appreciated!! :)

Richard

check CPU temp in bios if u can get in, might be HSF not properly mounted and CPU cutoff temp is being reached although it is a very short amount of time for that to happen. Other than that, check CPU temp shutdown setting in bios, if it is set too low it might be the cause. Also try cmos reset

I'd say an improperly mounted HSF is almost certainly the problem here. A naked P4 will get very hot very fast.

Also, check that you have the CPU heatsink fan connector plugged into the CPU fan header.....many motherboard shut down if it doesn't detect a fan spinning at a certain RPM on that specific connector.