# Computer won't turn on; Motherboard related??



## maniac779 (Apr 25, 2005)

I have a bizzare computer problem.

When I tried to turn on my computer, the power light came on momentarily and then shut off. I opened up the case to investigate and shut off the power supply and turned it back on. The motherboard stand by light was illuminated and I proceeded again to try and turn on the computer. Both the CPU fan and Video Card fan momentarily fired up and then shut right down again. Nothing.

I have detirmined for certain that it is not a power switch problem, or a power supply problem.

I'm assuming it somehow motherboard related or there is a breaker that has tripped somewhere, but I have no idea.

Any suggestions, cause I am stumped. HARD.


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## Sarkast (Sep 12, 2004)

How exactly did you "determine" its not an issue with the power supply ?
Is this a new build or a PC that ran for a certain ammount of time and just started doing this ?
If its not a new build - did you change anything recently ? Install any new components etc ?


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## maniac779 (Apr 25, 2005)

I know its not a power supply problem because I replaced it with a new one, and had the same problem.

I know its not a switch problem, because I reversed the power and reset switches and still no dice.

I've had this power supply for a year and this problem just happened today.


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## Welsh + Proud (Apr 25, 2005)

maniac779 said:


> I have a bizzare computer problem.
> 
> When I tried to turn on my computer, the power light came on momentarily and then shut off. I opened up the case to investigate and shut off the power supply and turned it back on. The motherboard stand by light was illuminated and I proceeded again to try and turn on the computer. Both the CPU fan and Video Card fan momentarily fired up and then shut right down again. Nothing.
> 
> ...


this was what was happening to me, i had to clear the CMOS and re-configure the BIOS settings again, also decrease in system performance and running much slower than supposed to.


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## Sarkast (Sep 12, 2004)

Well it would be helpful to know what your systems components are: CPU, RAM, motherboard etc.

Did you do a close physical inspection of your motherboard yet ? I'd take a very close look at the capacitors - bulging tops or leaks. Also anything else on the motherboard that seems unusual - discolorations etc.


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## ebackhus (Apr 21, 2005)

We had a similar problem with the Dells at the library I work at. Apparently they gave us a fleet of machines that didn't cool sufficiently and that caused many of them to fail. You can't even tell the damn things are on. I don't exactly know what the fix was because they don't think I'd understand. Anyway... We could plug in power and the mobo would light but it wouldn't power on at all. Try removing the board and power it on (on a SAFE surface) with minimal accessories and see what happens.


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## maniac779 (Apr 25, 2005)

Welsh + Proud said:


> this was what was happening to me, i had to clear the CMOS and re-configure the BIOS settings again, also decrease in system performance and running much slower than supposed to.


Did the system show these problems after you reconfiged CMOS/BIOS?

I have inspected the mobo and everything looks fine.

My system specs are as follows:

P4 2.4
Asus P4C800 Deluxe
1GB DRR Ram
ATI 9700 Pro

If I was to test the mobo on a SAFE surface, what would that consist of?

Thanks for the replies.


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## Sarkast (Sep 12, 2004)

What power supply are you running this on ? (i know you replaced it but was that model powerful enough ?)

A safe surface is something non conductive - i recommend a nice dry piece of cardboard.


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## maniac779 (Apr 25, 2005)

I was running this on a 400W supply for a year with no problems before this happened.

If I run the mobo on the piece of cardboard and it powers up, I guess I can assume it is shorting out somewhere on the case. However, if god forbid, my CPU or mobo is fried, how am I going to be able to detirmine which one is the culprit?


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## Sarkast (Sep 12, 2004)

First try setting it up that way - with minimum components.

If you still cant get it to post then its relatively difficult to know for sure if its the CPU or motherboard unless you have a diffrent CPU you can try. Of course theres always the local PC store you can take your motherboard to and see if they test it for you. 

I assume the physical inspection didnt return any results ?


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## maniac779 (Apr 25, 2005)

Physical inspection yielded nothing, everything looked normal.

I've run the systems with minimal componets. (CPU, RAM, Video Card) and still got nothing.

My next step will be to remove the motherboard and test it on a safe surface to see if its a short somewhere in the case. After that, who knows. I was thinking about a new machine anyway, maybe its time to start selling off the good parts on ebay.


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## maniac779 (Apr 25, 2005)

Okay, things may not be so bad afterall.

I've been fiddling with the 20 pin power connector and have been getting the board to power up, except the connector has to be in just so in order for it to work, and the configuration in which it will start is not when the connector is fully seated. Any suggestions?


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## maniac779 (Apr 25, 2005)

Okay, not so fast I guess.

I can get the fans on the CPU and the Mobo going, but the hard drive doesn't start to boot up. Also, once the fans are going, the power 'on/off' switch and the front of the computer has no effect on anything.


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## MD_Willington (Jan 11, 2005)

The fans run straight off of 12V the cpu does not, the cpu runs off the power regulation section of the mainboard..

Hard drives need more current from the 12V line to spinup than a puny fan requires...

Can you beg borrow or steal another power supply...they *do* fail...in fact the guts of the power supply may only be rated on average 5000 hours MTBR/F..that's a little bit under year or two of minimal usage depending on how long you run the PC each day...


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