CPU fan fails to spin up

[mal123]

I have installed a replacement motherboard for a dell optiplex 320. When in barebones condition, minus the cpu, the cpu fan spins up. But when I install the cpu (or plug in the cpu power supply) the board fails to power up. When I unplug the cpu ps, the board then powers up. I have tried two different cpu's, both have the correct notch configuration for the board. The first cpu is from the original mb, the second cpu I bought used from computer shop.

 

[KIll xd]

Tell me what kind of cooler are yuo using?

 

[price_th]

Almost sounds like the CPU you are using isn't supported.

 

[mal123]

Correction. The board powers up when I turn on the psu, but the cpu fan spins for a second and then quits.

It is a p4 3.4 cpu compared to the 3.28 that was on the old board. Installing the 3.28 has the same effect as the 3.4 (cpu fan spins for a second and then quits). This replacement mb has the same board specs as the old one. The cpu fan spins up when there is no cpu (or the cpu power is unplugged). So the problem is the cpu's or the zif socket.

Update: I've returned the mb for testing and/or replacement. This is impossible to diagnose without known good parts to test with.