Faulty Motherboard?

[maverick77_uk]

Hi,

A friend's computer was just cutting power sporadically, and he asked me what I thought the problem was, I suggested the most likely was a dodgey PSU. Anyway, he replaced his PSU, and asked me to take the PC and have a look at it as it wouldn't turn on anymore.

Its an ancient Celeron D, and he said to chuck it if it was knackered, so nothing major or valuable.

Anyway, I've had a look and tried 2 known working PSUs. When the PU is switched on at the back, the CPU fan turns briefly, suggesting to me all is well and good and connections are made. However, when the power button is pressed, its dead, nada, nothing.

I've tried unplugging all except essentials, just the 20pin power and 4 pin aux 12V, and all cards out. Still nothing.

I thought maybe it was something simple like a didgey power button. Tried shorting the power button pins on the MoBo directly. Nothing.

I'm now thinking there's something wrong between the power button pins on the MoBo and the point that gives the PSU the signal to turn on.

Does anyone have any suggestions? Or ever had a similar problem, ie it being dead, although the MoBo is capable of receiving power (ie the slight turn of the CPU fan)? There's no attempt at post, no fans spinning, nothing when the power button is pressed.

Or s it now just an oversized door stop?

Cheers all!

[s3ds]

I've just had to replace a mother board it started to cut out every 12-24 hours
Replaced the PSU with a known working one, same problem
After closer inspection of the mother board 4 capasitors were bulging on the tops.
http://en.wikipedia.org/wiki/Capacitor_plague

[maverick77_uk]

Hi,

Yeah, thought it might be that. Closely inspected capacitors and all look fine, oh well, to the dump it is!

Cheers!

[s3ds]

The only other things i can think of is
To remove all the memory and reseat one stick
Checking the board is not shorting on the case (the stand off's)
Remove the PSU plugs and check for bent/missing pins (i assume the PSU has been tested working)

none of the above are usualy the problem but it will not harm to check

[Behemoth]

You tried some different know working RAM on the board ? Seems that is more likely the route of the problem. Could also be the graphics card if it doesn't have an onboard one.

[maverick77_uk]

Hi all,

Thanks for your comments. It only has one stick of RAM, and yeah, I tried re-seating it. Also tried turning on the PC without it at all. In my experience, with no RAM (or graphics card, the computer spins up fans etc, but then immediately gives BIOS error beeps due to the missing bits. In this case, it doesn't spin up anything, just completely dead. Which is what I think it is!

[kalniel]

Sounds dead. Check the 20pin and 4pin power connectors for a bad connection perhaps? But it could be any number of things - VRM failure going to the CPU socket etc.

I've got a working harddrive-less 1ghz pIII if you want it mate (it's looking for a good home)

[WannaPiEcE]

The old power supply could have taken the CPU/Motherboard/RAM with it when it died. It happens.

[maverick77_uk]

Hi all,

Nope, its dead. He's already gone a bought a PC-World special (nooooooo...........!!!), but he's happy, so thats that.

Cheers all.