Nothing Happens When Power Switch Pressed

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Stylin80

Stylin80

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Oct 27, 2013
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Hello there. I'll cut straight to the point. I currently have a desktop that belongs to my friend that is unable to get any response from it. Absolutely nothing happens when you press the on button. The CPU and PSU fan doesn't even run at all.

I have already done some tests on the different parts of the desktop and I'm left with these 3 parts which I've yet to/ unable to test due to lack of spare compatible desktops to test it with.

They are the :
- Motherboard ( FoxConn B75M )
- CPU ( i7-3770 )
- Front panel of the casing.

Among these three items, which one is most likely to cause the issue that I am facing? ( I'll update in a few moments regarding the functionality of the front panel)

Thanks.

Just in case you might need them, here are the specs.
CPU: Intel i7-3770
Mobo: FoxConn B75M
RAM: Apacer DDR3 4GB
GPU: Nvidia GeForce GT610 (Leadtek)
PSU: mBoss ATX PSU 500Watt

Update 1: The front panel switches work as well. Confirmed it via connecting it to another PC and successfully booting it.
 
Solution
geofelt
Sounds like the motherboard failed.

And... I do not know the quality of that psu. It is not a known good quality brand.
Possibly it contributes to the failure with some sort of power overload.
It may work, but I think I would replace it with a quality unit regardless.
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Rookie_MIB

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Jul 27, 2013
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Agreed. Bypass the switch first. Briefly connect the two pins together which are the PWR + and PWR -. If the computer comes on, then it's the switch. Going to say, probably pretty unlikely, usually those don't go bad (but it has happened to me before...)

Next would be to test the PSU - you can either swap with a known good one and see if that one works, or you could disconnect the main ATX 24pin connector, and short the green wire with any black wire. If the PSU doesn't go on, then it's the PSU. If it does go on, it still -might- be the PSU (it might be functional, but unable to supply the amount of current). If it does go on I would open up the PSU cover carefully or shine a light into the top fan of the unit (do NOT touch any capacitors and wear rubber gloves to insulate your hands!) - take a look at the capacitors, if there are any bulged or leaking on the tops, then replace the PSU.

I would also say it's most likely NOT the CPU. I have yet to see one of those die as well.
 
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geofelt

geofelt

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Oct 9, 2006
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Has anything changed on this pc that was presumably running before?

In order:
1. Short the two power on pins in the motherboard. That should eliminate the front panel or wires as an issue.
2. Motherboard failure is next on the list. If the cpu was remounted, it is easy to bend socket pins which will cause all sorts of failures.
3. Intel cpu failures are extremely rare.

Remove the motherboard from the case to do some testing. Possibly, you have a short to the case.

How did you test the psu? The paper clip test is worthless.
The quality of the psu is a prime suspect. See if you can't test with a known good psu.

If no joy, replace the motherboard.
 
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Stylin80

Stylin80

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Well, I've just tested the front panel to check to see whether was it the issue and it's a no. I've connected that front panel to another PC and it was able to boot it up just fine. I did try to short it as well but nothing happened.

As for the CPU remounting, I can confirmed that that is not the issue as I've checked the pins whether are they bent or not earlier today. All of them as perfect.

For the PSU, I can confirm too that it is working because I've connected it to another similar PC and it works just fine as well.


As for my own theory, I do agree that it is quite unlikely that it is the CPU is broken. I do agree that I think it is the mobo that is broken as well. However, I've fix my fair share of PC's and I've never come across a total failure of the mobo. I mean as far as I've experienced, although the mobo might have failed, at the very least, the PSU fan or CPU fan would still run at a slow speed when the power button is pressed. Never seen before a complete silence from it before.
 
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geofelt

geofelt

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At this point, I think it has to be the motherboard.
Possibly there was a power surge?
Is there any evidence of burnt components on the motherboard?
The last time the pc ran was it shut down normally?

If it was the cpu, you would get at least some fan activity.
 
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Stylin80

Stylin80

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Well, my friend said that in its last moments, when he was trying to boot it up, it just died ( sudden black screen as though as power cut out ) halfway booting. So he tried again, and it booted slightly longer then before but still died again. Well when the third time he tried again, nothing happens anymore. As for evidence of burnt components, well, visually inspecting, no. However, there is a weird smell from the PC I've just noticed. Its origins is from the mobo and it smells of either spit ( Don't ask how I know how it smells like ) or some sort of chemical. Possible burnt part of the mobo?
 
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geofelt

geofelt

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Oct 9, 2006
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Sounds like the motherboard failed.

And... I do not know the quality of that psu. It is not a known good quality brand.
Possibly it contributes to the failure with some sort of power overload.
It may work, but I think I would replace it with a quality unit regardless.
 
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Solution
Stylin80

Stylin80

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Oct 27, 2013
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Yeah I agree as well that it would most likely be the mobo failure. And same as well, never heard of this brand of PSU as well. I'll forward this info to my friend. Thanks alot!
 
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