PC powers up for a few seconds then switches off...

fingers88 · § #1 11-06-2009, 12:32 PM

Hi all, I built a PC 2 years ago and it's been fine until recently. I re-imaged the HDD and now the PC will power on for a few seconds (fans start, LEDs on) then switch itself off again, and without doing anything it does the same thing again and again, then I have to switch it off at the PSU switch.

I've opened it up cleaned it from dust to make sure it's not shorting but the problem is still present. I want to avoid stripping it completely for a proper clean. However it will start normally (sometimes) with the side off, but when the case is closed it does the same thing. I can close the case once started but when I power on afterwards it does the same thing. When it does run (with case open) it seems fine, had it running overnight doing animations without problems. Other freaky things are it's switched itself on a couple of times in the middle of the night (it's connected to a UPS).

I don't think it's overheating, having the side panel off seems to help. I have removed all the devices attached to the USB header pins and it seemed to solve the problem for a few days, but the problem is back.

I'm sure it's a shorting issue and I'm going to stripe it down to make sure but if anyone has a solution I can try before I do that it would save me a huge amount of pain.

Anyone got any clues, as this has me completely stumped.

Pixels303 · § #2 11-06-2009, 12:50 PM

Check the capacitors on the mainboard. See if you find a leaking substance coming from under them or if the tops of the capacitors are no longer flat but rather a little bit Convex in shape. Electrolytic Capacitors are can-like components which look like small batteries which are attached to the mainboard in a radial manner. (Two leads on one side) Capacitors are replaceable if you have the tools and extra parts, or simply buy a new mainboard if they are damaged.

Try switching the power supply to see if it will work with a different power supply. Does the fan turn in the power supply?

Yeah · § #3 11-06-2009, 01:08 PM

Quote:

Originally Posted by fingers88

....... SNIP

I don't think it's overheating, having the side panel off seems to help. I have removed all the devices attached to the USB header pins and it seemed to solve the problem for a few days, but the problem is back.

.... SIPPED

Anyone got any clues, as this has me completely stumped.

Ok.. I know you think its a shorting issue, but I really doubt it. It sounds more like heat related. Especially if you say having the side panel off seems to help...

Does the side panel push up against any wires or the motherboard when you put the panel on? If not.. its most likely heat. Are you sure the CPU fan is spinning up correctly and not being inadvertainly slow sometimes?

Is there a fan on your north bridge? Is it spinning up and not looking slow?

Only other two things I can think of would be like pixel said capacitors leaking and or bad/ going bad PSU.

mpulliam · § #4 11-06-2009, 01:29 PM

Sounds like heat - and/or PSU.

Make sure your Heat Sink/Fan are attached properly still. A simple test is to place a small room fan blowing into the case with the sides off - does it stay on longer? Heat issue.

Repeat reboot? Then I would look for blown caps (is this a s:478 or s:775 board?) P4 were notorious heaters - I had one that I OCed and if it got a thin sheet of dust it was enough to shut down.

Also, you say it was workign fine, then you re-imaged - what program did you use to ghost the drive? There may be a BIO's/Driver problem. Can it boot in Safe Mode?

Yeah brings up a good point too, some of those 40mm fans were garbage and died just for looking at them wrong. Verify it is spinning.

-=M=-

fingers88 · § #5 11-06-2009, 03:36 PM

Quote:

Originally Posted by Pixels303

Check the capacitors on the mainboard. See if you find a leaking substance coming from under them or if the tops of the capacitors are no longer flat but rather a little bit Convex in shape. Electrolytic Capacitors are can-like components which look like small batteries which are attached to the mainboard in a radial manner.

(Two leads on one side) Capacitors are replaceable if you have the tools and extra parts, or simply buy a new mainboard if they are damaged.

Try switching the power supply to see if it will work with a different power supply. Does the fan turn in the power supply?

Thanks for the hint, I'll have a look into that and report back. I don't have another PSU to test but once I've eliminated the other aspects I'll try that. Obviously I want to avoid buy new parts for now.

Quote:

Originally Posted by Yeah

Ok.. I know you think its a shorting issue, but I really doubt it. It sounds more like heat related. Especially if you say having the side panel off seems to help...

Does the side panel push up against any wires or the motherboard when you put the panel on? If not.. its most likely heat. Are you sure the CPU fan is spinning up correctly and not being inadvertainly slow sometimes?

Is there a fan on your north bridge? Is it spinning up and not looking slow?

Only other two things I can think of would be like pixel said capacitors leaking and or bad/ going bad PSU.

I think the wires from the cases power switch, reset button and HDD LED may touch the side panel, I'll have to check that out. The other reason I don't think it's heat related is I have had it running for over 20 hours doing animation, (but I think the side panel was off) still the problem with it repeat rebooting doesn't appear to be heat related not if it will boot into windows. However I am prepared to investigate if it's heat issue, the heatsink fan spins normally as far as I can tell.

Quote:

Originally Posted by mpulliam

Sounds like heat - and/or PSU.

Make sure your Heat Sink/Fan are attached properly still. A simple test is to place a small room fan blowing into the case with the sides off - does it stay on longer? Heat issue.

Repeat reboot? Then I would look for blown caps (is this a s:478 or s:775 board?) P4 were notorious heaters - I had one that I OCed and if it got a thin sheet of dust it was enough to shut down.

Also, you say it was workign fine, then you re-imaged - what program did you use to ghost the drive? There may be a BIO's/Driver problem. Can it boot in Safe Mode?

Yeah brings up a good point too, some of those 40mm fans were garbage and died just for looking at them wrong. Verify it is spinning.

-=M=-

It's a s775 board, not overclocked all standard. I re-imaged as I had a virus from trialing software, I used Acronis True Image 10. Again I don't think it's software related as it will boot into windows fine when it gets past the initial boot stage. When it repeat reboots (the best description BTW) it does it after about 5 seconds, I don't have to touch anything. Also it has switched itself on in the middle of the night.

If it is a heat problem or PSU what is happening/has happened since as it's been fine for over 2 years.

mpulliam · § #6 11-06-2009, 03:55 PM

Quote:

If it is a heat problem or PSU what is happening/has happened since as it's been fine for over 2 years

Computers are almost always in some sort of "decay" from the time they are built - normal heat is the main culprit, dust/static being a close second. PSU do have a shelf life. I have had customers with a box that runs great for 4-5 years (or more for some) then they reformat and the crud hits the fan. The reformat was just the catalyst.

Being a s:775 board gives me confidance that it isnt a cap issue.

I would take an old hard drive, reformat it, reinstall a fresh OS onto it and let it rip. Does it function? If yes, then that points to a borked ghost on the orig drive.

Actually before this step, remove all the ram, and video card. Blow it out. Use 1 stick of ram, and onboard video (if an option) and reboot. If possible use an old video card you know that functions if you do not have onboard vid.

**Sick Willie** · § #7 11-06-2009, 04:44 PM

It could be a bad power switch. This switch is a momentary switch and if it becomes shorted will exhibit the exact behavior you describe in the first sentence. Though rare, I have encountered it. Unplug the switch from the motherboard and short the pins on the board to start the machine. If it stays on, you've found the culprit -it's either bad or the wires are shorting somewhere.

fingers88 · § #8 11-07-2009, 12:16 PM

Quote:

Originally Posted by mpulliam

Computers are almost always in some sort of "decay" from the time they are built - normal heat is the main culprit, dust/static being a close second. PSU do have a shelf life. I have had customers with a box that runs great for 4-5 years (or more for some) then they reformat and the crud hits the fan. The reformat was just the catalyst.

Being a s:775 board gives me confidance that it isnt a cap issue.

I would take an old hard drive, reformat it, reinstall a fresh OS onto it and let it rip. Does it function? If yes, then that points to a borked ghost on the orig drive.

Actually before this step, remove all the ram, and video card. Blow it out. Use 1 stick of ram, and onboard video (if an option) and reboot. If possible use an old video card you know that functions if you do not have onboard vid.

That's fair enough about the reformat. I suppose having re-imaged with the same image file in the past and it's been fine I think it's a hardware issue but I'm prepared to try anything.

As for the capacitors as far as I can tell they all solid state , it's an Abit AB9 pro motherbaord.

Quote:

Originally Posted by Sick Willie

It could be a bad power switch. This switch is a momentary switch and if it becomes shorted will exhibit the exact behavior you describe in the first sentence. Though rare, I have encountered it. Unplug the switch from the motherboard and short the pins on the board to start the machine. If it stays on, you've found the culprit -it's either bad or the wires are shorting somewhere.

I have looked into the power switch, I can't remember what I've done, I have booted it up without the switch connected to the motherbaord but can't remember if it still repeat reboots. I'll look into it again and make sure I do some proper elimination tests. Thanks for the suggestion.

fingers88 · § #9 11-15-2009, 11:40 AM

Well it looks like it was a faulty power switch, so top marks to Sick Willie. I swapped it with the reset and that stopped the problem and now it's been replaced it seems back to normal. I've got to replace the USB devices to the header pins but I don't think that will be an issue.

Thanks to all those who posted helpful responses.