Power supply starts, then immediately stops

[ccr]

The computer has recently been moved. Before the move it worked. Nothing dramatic happened during the move.

When I press the start button, the light comes on. The power supply fan starts and the CPU cooling fan starts. Then after at most 3 seconds, the power supply shuts down (both fans stop). But the start button light remains on.

I took out the power supply and tried it on another motherboard (without any other loads). It seemed to work fine. It wasn't connected to any drives, etc.

After putting the power supply back in, I bypassed the start switch on the computer by just shorting the terminals on the MOBO. Same results. I checked the CPU to make sure it was seated correctly and as best I can see, it looks OK. I unplugged the power from all the drives etc. Same failure.

I also took out the CMOS battery for 10 minutes, then put it back in. Again no help.

As best I can figure, the motherboard is telling the Power Supply to cut off.  Any ideas what other tests I could do to tell what's happening?

[squirrel]

Do these steps:
Take all your parts except the motherboard out.  Switch all the parts with those of another computer. If it does the same thing with the other set of parts, it is a motherboard issue. If the power supply fails to work on the other machine, switch the hardware back--one device at a time, trying the computer after each device. BTW--make sure computer is unplugged BEFORE removing hardware, then plugged IN before testing.

[Fed]

This is an interesting article.
http://www.zzine.org/read.php?op=view&item=411
I'm not sure that trying it in another computer proves that it's OK. If you tried a different one in the offending computer?

[ccr]

I will try a different power supply before I go for a new motherboard. I'll have to rip one out of another box. No spare! It's worth a shot.

[2k dummy]

Before you go out and buy new parts - since you will be dismantling the thing anyway - check to see if one of the MB standoffs has become dislodged. This can cause a short and immediate shutdown. Also check to see if the heatsink is making proper contact with the processor. Even if the processor is well seated, if there is not good contact between it and the heatsink it too will cause immediate shutdown due to overheating. These are the most common causes of your problem.

[merlin_2]

Is this a self-build pc!

[ccr]

No, not self built. emachines.

[merlin_2]

mobo had it!

[batman1071]

dude i think you've got to buy a new power supply

[ccr]

Update: I just pulled a working power supply and connected it to the offending machine. Same results.  


I'm feeling pretty confident that the MotherBoard is shot. Now, how the heck did that happen?!!!!  

[merlin_2]

Something loose in the case fell on to the mobo maybe!

Visually inspect the board for .....for tracking<eye line cracks,hold up to a light source> burning,capasitors learning over!! did his board have an amd cpu!

Recking wiring plug banks! on the board!and all ramsticks/graphics card:

Before comdeming the board!

[Frankie]

This Happend to my computer once, It turned out to be the heat sink and fan. Like yours my computer would boot up for 3 seconds. Fans spun round, then it would just shutdown. I replaced heat sink and fan and it worked fine after that. Im not saying this will definatley work for you, but it just sounds the same as happened to my computer. Let use know what it was when you fix it, will be intesting to see what caused it.

[2k dummy]

I told what to look for ^up there^. Apparently prefers replacing to checking.

[Raptor]

I told what to look for ^up there^. Apparently prefers replacing to checking.

Some people just never learn to scroll up, aye.  :-/

[ojas25]

It sounds like that the fan is not working or the clips holding the heat sink on have come lose this happened to me today checked the heatsink clips and one was not clamp down properley,  push it down until it click into place,  and no more trouble computer working fine. Or the fan maynot be running fully the bearings do wear out after a while if that's the case just replace the fan, If you can. If not buy a new heatsink.