Computer shuts off if nudged or bumped

A

alexymik

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Jun 5, 2013
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This is an older system of mine I spruced up in hopes of selling since I don't need it anymore. However, it's decided that it's a perfect time to start acting up.

What is happening: A light to medium nudge will instantly cut the power to the system. It's able to start up fine but the same happens if nudged again.

Basic Specs:
EVGA nForce 780i LGA 775 Motherboard
Intel Core 2 Quad Q6600

I suspect there is some kind of short going on and I've tried to isolate it as best I could with no luck. I've taken the motherboard out and placed it on my desk without any peripherals. I've taken out all the RAM modules except for one. I've also tried a different power supply and different power cable. Tried to reseat the CPU as well. Lastly I've tried to gently press and tap various parts of the motherboard with a plastic screwdriver handle but can't get it narrowed down to any particular area.

Basically I'm out of ideas. Is this motherboard toast?

Thanks for any help.
 
Unplugged and checked all PSU connections?

Tried removing it to minimum components required and booting?

Motherboard earthing?

It sounds like a dry solder break to me but the above issues have foiled myself and others in past. Good luck.
 
My old EVGA 775 boards were notorious for the SATA ports breaking relatively easily.
 
Maybe one of the buttons or button wires in the case is shorting to ground? Or maybe a fan.
 
When the board is running without the case, if you tap the board it powers off in that scenario? If so, that sounds like an actual problem electrically with the mobo and yeah it's probably done for, assuming folks occasionally nudge your system. I could probably operate with a system that had that issue for... years, since my PC is out of the way and nobody ever touches it. It would make plugging in USB peripherals very nerve wracking though.
 
>>I suspect there is some kind of short going on and I've tried to isolate it as best I could with no luck. I've taken the motherboard out and placed it on my desk without any peripherals.

I'm not clear on what you found here.... does the mobo fail out of the case or no?

With everything out of the case, you should be able to isolate the problem easier.
You can pick up the PSU and tap on it, move wires, etc.

Look at the ATX power connector, it might be a cracked pin on the back side of the mobo.
It could also be a burnt pin on that connector.

.
 
Hi all, thanks for your ideas.

To clarify a bit, the system does this with the motherboard/CPU/RAM only and nothing attached. I had it on my desk on an ESD workmat with a different PSU to test. The motherboard features built in power buttons so I was using those.

Only other things I can think of is to try a different CPU and to more closely inspect the motherboard for any kind of visible damage.
 
Sounds like a bad connection on a power or earth rail.
Perhaps a cracked solder joint or poor connection where there is potential stress.
ie a motherboard power connector, psu lead/connector ...
 
alexymik said:
Hi all, thanks for your ideas.

To clarify a bit, the system does this with the motherboard/CPU/RAM only and nothing attached. I had it on my desk on an ESD workmat with a different PSU to test. The motherboard features built in power buttons so I was using those.

Only other things I can think of is to try a different CPU and to more closely inspect the motherboard for any kind of visible damage.
Click to expand...


Tap the sides of the on-board power and reset switches with a pen in case one of them is bad.

A lot of the time this stuff is related to one of the power pins.
Check the back side of the mobo carefully for any cracked solder on the pins.

.
 
Look for a thread in the forum about baking your video card. It is possible that the same technique might work for you also. The problem could stem from "solder whiskers" caused by the use of lead free solder (thank you very much RoHS), If nothing else works, what have you got to loose? The board is not useful as it is, right?

EDIT: The thread is here.
 
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I had an issue with my computer shutting off or the video cutting out and then cutting back in after a couple seconds.

Turns out I had a faulty front USB port that was getting shorted out.

It took forever to figure it out though. With such an old setup OP, use this as an excuse to upgrade. Hah!
 
I would remove all varraibles. Remove psu from case inspect all wires, disconnect everything not needed. Disconnect all front panel connectors (audio, USB, buttons) hook up psu outside of case. Then Power it up manually jumping the pins and move the case and external psu around. Once you know it's not the psu grounding something reinstall it in the case and test. Then start plugging things in one at a time.

The problem should present itself.
 
There are probably several others but I just ran across this baking video from Linus Tech Tips. It's kind of comical but he covers the basics. He managed to recover a GTX 780Ti but not an Intel 750 PCIe SSD.
 
Sounds like some solid advice to try here. I have the same issue with my HTPC. My solution was lazy and won't really help you out since you are planning on selling it, but it worked for me.
I just bolted the whole damn full tower to the wall about 3 feet from the floor and called it good.

Best of luck figuring it out!
 
No I know what it is, it just seemed like going from step 1 to 50 skipping everything in between.
 
s10010001 said:
No I know what it is, it just seemed like going from step 1 to 50 skipping everything in between.
Click to expand...
:D Well, it looks like he has already done almost all he can short of changing the CPU and a microscopic inspection of the motherboard (see post #7). Granted baking the board is a last resort measure but the board can't be effed up much more than it already is. :arghh:
 
Yea I didn't see that until after...I'm still leaning on a psu cable problem. Maybe pulled to tight or something
 
Does your board have the buttons to turn it on or reset or access the bios?

Check the continuity on them. They could have broke and are shorting the pins when you nudge it.
 
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