Computer turns on for 3-4 seconds and then turns off (dead CPU?)

[Kaducii]

Hi everyone,

I'm currently in the process of changing motherboards as my old one is dying so I know all of the parts are working. Right now I have just the bare minimum plugged in to test the connections, Radeon X800xl, 1 seagate 120gig 7200.7 HD, 1 case fan, 1 stick of ram OCZ 3200 1gig. All the jumpers and motherboard to case connections are set correctly.

When I press the power button, everything would power up for 3-4 seconds and then power back down. I initially thought it was a short circuit problem or something with the motherboard but when I tried testing everything one by one, I found that when I unplug the 4 pin square CPU cable from the PSU to the mobo, power is normal and the fans are spinning. When I plug it back in, the 3-4 second power up/down occurs. Do you guys think that's a CPU problem or could it still be a motherboard problem? I tried unseating the CPU and reseating it but that didn't work. I'm working with a AMD 3700+ s939 CPU and a ASrock SATA2 S939 board.

Any help would be much appreciated.

 

[TOAOCyrus]

Try testing the CPU in another motherboard? Also clear the CMOS and see if that helps.

 

[Kaducii]

Thanks for you quick reply,

Just tried clearing CMOS. Still have the same problem.

I'll try testing the CPU on my *old* mobo.

 

[sgrinavi]

Sounds like a PSU problem to me...

Are you sure the old MB is what's crapping out?