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I can't quite pinpoint this problem.

About 6 months ago I purchased an incredibly cheap computer case, and an incredibly cheap power supply from NewEgg.

After I overloaded the powersupply 'til the point it was literally smoking. I removed some of the extra video cards (this was a gpu cluster computer) and proceeded as usual.

This one incredibly annoying thing kept happening. Whenever I would go to plug in my computer monitor to the back of the computer... there was a 50/50 chance the machine would shut off right away.

I immediately thought it must be the power supply. Mainly because I had driven it to the point of smoking. So I removed the power supply and replaced it with a high quality, gold+ Antec PSU (and changed out the motherboard, cpu and ram while I was at it).

Low and behold, the computer persists to switch off miraculously simply by touching it.

Again, this does not happen all of the time. I have noticed it depends where I touch it exactly. Towards the top of the case (where the power and rest buttons reside) is where it is most vulnerable.

Any ideas?

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migrated from serverfault.com Sep 27 '11 at 12:31

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2  
Sounds like a problem with a short/ground. Off topic for SF though. –  jscott Sep 27 '11 at 12:26
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incredibly cheap: In other words, you wasted money on stuff you had/have to buy again in decent quality. Congratulations. –  SvW Sep 27 '11 at 12:28
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Agreed, a short in the wiring.electrical, possibly a bad connection between the MB and PSU. Not a power button issue, that takes ~5 seconds to turn a computer off. –  Chris S Sep 27 '11 at 12:31
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What's the maxim? Computer Power Supplies: Buy Cheap, Buy Twice. –  tombull89 Sep 27 '11 at 12:37
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that actually applies to almost anything, and is a great rule of thumb / reason to get fancy things. –  Sirex Sep 27 '11 at 12:40

2 Answers 2

up vote 3 down vote accepted

well, considering how simple modern computer power switches are. possible but unlikely. The good news is its a simple thing to just bridge the two contacts for power to test it. Bad news is this could indicate a fault somewhere else.I would try running the system with the power switch unplugged, using something else (I have switches pulled from old cases 'in case' but i've switched on systems with a penny before).

I'd note computer cases, while metal, are painted so.. a short would be unusual.

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Great idea, "try using the system with the power button unplugged", it was most definitely the power cable. I just didn't think to try that because, well, I couldn't turn it on (conventionally). Just as I had thought. A $1 piece of equipment was the only culprit in my cheapo system. No need to throw the baby out with the bathwater, I'm looking at you, SvenW ಠ_ಠ –  darkAsPitch Sep 30 '11 at 12:31
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well, it could be a short anywhere along there. shouldn't be too hard to visually inspect and patch or replace it. bonus points for replacing it with a knife switch ;). I've worked with some fun situations (caseless PCs, and junkyard revivals) so that was the obvious possibility –  Journeyman Geek Sep 30 '11 at 14:11
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+1, however, I have seen bad power buttons quite a few times! Anything from the hinge (from button to case) gone to the spring inside - this can make them really flimsy and sensitive... so... I wouldn't rule it out! –  William Hilsum Sep 30 '11 at 14:46

Does your psu have a short or surge protection circuit or switch? One thing you could test to see if it's a shorting issue is screw an earth to the inside of the top of the case, if it doesn't turn on at all then there's a short circuit somewhere on the case.. however I'd be surprised if this was the cause, if it was you'd probably feel the shock when you touched it.

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Again. PSU was switched out and the problem persists. This had nothing to do with the PSU. –  darkAsPitch Oct 1 '11 at 14:27
    
I was more suggesting it was an issue with the case shorting somewhere. –  Alex Berry Oct 5 '11 at 8:20

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