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Help! Computer won't power up

minkey
Grafter
Posts: 386
Registered: ‎22-07-2007

Help! Computer won't power up

Hi
I am trying without much success to fix a computer which will not power up. I have changed the PSU to eliminate any power problems but the problem remains. When I turn it on, the fans turn for about 1/2 a turn then stop and nothing else happens after that. If I remove the 4 pin (2x2) +12v connector the fans turn properly but the computer will not POST.
The motherboard is a MSI MS  7255.
Does anyone know what else I can try to fix the computer or what is wrong here?
Thanks
Jeff
11 REPLIES
Community Veteran
Posts: 1,850
Registered: ‎11-08-2007

Re: Help! Computer won't power up

you could change the coin shaped battery on the motherboard, though i doubt that's the problem.  more likely the power supply.
Moderator
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Posts: 27,325
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Registered: ‎14-04-2007

Re: Help! Computer won't power up

Could be a failed component on the motherboard in which case it's a replacement.

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Community Veteran
Posts: 14,439
Thanks: 728
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Registered: ‎01-08-2007

Re: Help! Computer won't power up

Quote from: artificer
you could change the coin shaped battery on the motherboard, though i doubt that's the problem.  more likely the power supply.

Didn't you read the post? He's already replaced that to no avail.
It sounds to me like the motherboard has failed. I've experienced these very same symptoms myself when my GF's computer came back from her brother. Everything was dead and the fans would just about flicker. It's a pain because then you don't know what else works unless you try it in another mobo. If you're unlucky like me you'll end up destroying other parts in the process. I managed to destroy a nice AMD processor by trying it in that board....
It's a real pain to be honest. I'm afraid repairing it is a case of trial and error.
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pierre_pierre
Grafter
Posts: 19,757
Registered: ‎30-07-2007

Re: Help! Computer won't power up

ignore
Moderator
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Re: Help! Computer won't power up

All suggestions welcome Smiley

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minkey
Grafter
Posts: 386
Registered: ‎22-07-2007

Re: Help! Computer won't power up

Quote from: okrzynska

It sounds to me like the motherboard has failed.
...
It's a real pain to be honest. I'm afraid repairing it is a case of trial and error.

That's what I suspected  Sad  Although I was hoping for some miracle.
Quote from: Strat
All suggestions welcome Smiley

Yes definitely  Smiley  thanks for all your sensible suggestions.
I was reading the manual for the motherboard and the 2x2 pin connector powers the CPU. Would a failed CPU account for the problem or is more likely the motherboard?
Thanks
Jeff
Community Veteran
Posts: 6,735
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Registered: ‎02-02-2008

Re: Help! Computer won't power up

In most cases you cannot tell if it's processor or board, and trying to find out risks wrecking something that was working.
A badly-seated memory card can cause the problems you describe, so swap them around a bit and try it with none at all (should get some beeps).
Unless there's a big disparity in price betweem motherboard and processor (in which case get a spare of the cheaper one) just assume they're both suspect and buy a new set.
mathewrennie
Dabbler
Posts: 24
Registered: ‎23-10-2008

Re: Help! Computer won't power up

Hi,
Sounds as though your processor has a bent pin or overheated..! Check your processor.
At a guess I think the motherboard is fine, as power is travling around the board correctly... as you said when you press the power button it turns on for a second. Try another processor in the board and check all your wiring, also check under the board for any screws/metal that may have went behind it, this can cause a short circuit..!
Cheers,
Mat

techguy
Grafter
Posts: 2,540
Registered: ‎12-09-2008

Re: Help! Computer won't power up

Bent CPU pin or board has gone to that great fabrication plant in the sky.
Community Veteran
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Registered: ‎13-04-2007

Re: Help! Computer won't power up

Does it give any video out put or any beeps if so how many. Normally if it turns on for a few seconds it has found a fault with the possessor getting to hot or the system fan isnt registering as working so it shuts down to stop overheating.
You should clean the cpu heatsink and the fans to get rid of any muck possibly try another system fan press down on the heat sink when you turn it on to ensure its in contact with the cpu. If all that fails remove the heatsink and apply more past to the cpu. Check usb connections and remove them if the plug into the board a faulty usb can short the board out and would give this type of error check any on the MB to ensure they are not shorting
Community Veteran
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Re: Help! Computer won't power up

Quote from: mathewrennie
Hi,
Sounds as though your processor has a bent pin or overheated..! Check your processor.
At a guess I think the motherboard is fine, as power is travling around the board correctly...

I must strongly disagree. A CPU pin won't just magically bend while its in the motherboards processor socket. You are correct though in the fact that it could of overheated and burnt out.
I also disagree highly with your statement saying the motherboard is fine. I very much doubt it is. I've had these exact same symptoms. Just because the fans turn on doesn't mean the entire motherboard is fully functional. The bios chip could be corrupt, the memory interface slots may be defective, there might be dead capacitors, diodes that have blown etc. Just because part of the motherboard that controls the fans works it doesn't mean the rest of the board is fine. Thats like saying because the starter motor on a car works the entire engine is faultless even though it won't start.
I've had to sort a computer with these exact same symptoms. Totally dead. Put in my spare processor to test the board and it fried that too. The PSU was also a gonna if I remember correctly (It's still upstairs in the cupboard awaiting a rebuild). The motherboard was history yet despite that there was still some basic life from the cooling fans. Despite that the board is DEAD.
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