Booting problem

Hi, im trying to fix a dell 8400 for my freind however i have met a strange problem.

The pc wont boot without resetting the cmos, then it works fine. However turn it back off and the cmos needs to be reset again.

Without the reset the psu and f ans dont even spin up and no lights come on apart from the aux power light, showing the psu is getting power.

Any ideas??

Thanks, neil.

Follow Me

Needs a new cmos battery.

Ive tried another which afaik is ok and im still getting the same problems unfortunately, but ill try the one from this machine just to be certain.

BIOS update?