Motherboard?

R

Rod Bishop

Member
A coworker brought me a HP Pavilion 700 yesterday, it was so called dead.

I noticed inside when I plug in the pc power cable the motherboard cooling fan fires up for 2 seconds and stops.

I tried two more power supplys anf the results are the same, just alittle spin of the cpu fan. I know the two PS units are good.

There are no visible signs of damage or bad caps on the motherboard so I'm stumped.

It the simple spin of the cpu fan a sign of anything special? I think most fans kick a little on power startup.
I pulled the ram, pulled all slot cards, still nothing, not even a beep.

Any ideas on this?

Thanks
 
Try resetting the cmos. Unplug power from pc, remove cmos battery, press and hold power button for 10 seconds, then wait 10 minutes, then reinsert battery and reconnect power and try booting up.
 
no Change BUT

I tried the CMOS idea but nothing changed...

Today I got another PC with the same type problem, but from a different friend, When one finds a guy who works on PCs, the sky is falling..

This other PC is a DETEL brand that I'm not found before. The system does exactly the same thing as the orginal system.

With the case open, as I plug in the power cord the cpu fan spins a little and the case cooling fan spins a few times but thats all.

On the second PC there is a led on the motherboard that is on but thats all.

Any ideas on either PC with the same kind of trouble.

Both were a gift, the owners wanted to throw them out but I enjoy the mystery.
 
Remove the memory and see if you get some beep codes from the motherboard. Also remove the CPU if the memory test didn't work and try again.

The mobo has to have a speaker onboard to do it.
 
I Tried something new

Today I plugged in the power cord to the PC and still nothing. with all the cables plugged in I unplugged the yellow and black cpu cable and all the fans came on. The cpu fan the case cooling fan came on.

I unplugged all the cables except the 20 pin cable and the two fan cables and connected the psu power cord and the fans came on again.

When I plugged in the cpu cable again everything cuts off.

This is a psu from a working system so I know it's a good one.

Any ideas

Not enough power? Motherboard shot?

No signs of any outages on the motherboard, all caps look fine, no shorts.
 
And yet no loose screw or a standoff in a wrong place?

You have a PSU that's known to work but is it underpowered for this system?
 
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