My computer is shutting down spontaneously !!!

[Felecha]

Never saw anything like it! My computer has been shutting down spontaneously.

Custom built at a local shop. ABIT KT7-RAID, Athlon Tbird 900, 256RAM, 98SE, 300W powersupply, what else?

Today I slid it out from under the desk to put the cover back on, which has been off for a week or so since I had to pull the NIC too many times and got tired of removing the cover. Another story. After a week with no NIC problems, decided to replace the cover. As I slid it back under, it just conked out! Died right there, whirred down to silence. I thought maybe the cord had been pulled? The cord was in tight, and the other end in the CyberPower UPS was good. I wiggled the plug on the computer end again, and hey! it came on, then died again after a few seconds. Oh no!! What's wrong here? A couple of more times on and off by wiggling, then I found that merely moving the box around could do it. On and off without touching the switch. Various manipulations of the case (it's not a perfectly rigid box, of course, you can flex it a small amount , even with gentle moves). Curious! And scary. I wondered if the UPS was a problem, but the same syptoms happened when plugged straight into the wall.

Finally got it to stay on, left it the rest of the day without touching it at all, called and found the guy who built it was out. Then this evening it just died again without my touching a thing. And then I noticed that it didn't just fall over dead at once, it closed the one open program, did the doodle-doodle sound in the floppy drive like it does when it shuts down with C-A-D, the screen went blank, and it shut off. It didn't just die, IT SHUT ITSELF OFF!!!

I tried a few more times, and it's true -- if it's got all the way booted up and running, it doesn't die, it shuts off. I didn't notice that at first because I was under the desk at the time.

The UPS has the automatic shut-down software that turns it off if no action from the user after 5 minutes of running on battery. Maybe that's involved?

I've got many months left on the one free year of tech support at the shop, but I hope to not have to turn it in and lose the use of it for days. I need it for school many ours a day and have no real alternative. All my crucial software is on it.

This is scary. Any help?

 

[moocat]

If it isn't your UPS acting up it could be your power supply.

 

[Felecha]

As a rookie, I could only think that if the powersupply itself were "cutting out", it would just drop dead, go black in an instant, just like if you pulled the cord out. How could it get triggered to shut down?

I posted first from my wife's machine. now I'm on my own machine again. Got it to boot after lots of wiggling. I uninstalled the UPS auto-software, and changed all the power management settings to never, at a friend's suggestion. Maybe that will do something?

F

 

[Felecha]

Nope, that didn't change anything.

But now it's doing something I can describe as consistent. When I find a way to move it around and get it to start -- the best seems to be to hold the top front corner of the tower and the bottom rear, and give it a gentle "twist" to flethe case a bit. It's a full tower, so it's tall and narrow. And what happens is that when it does start up, it gets to the point where it beeps at me after maybe 4 or 5 seconds, and then dies one second later. Out of 20 or more trials, only once has it gone past that point, and that time it booted all the way and I posted from there. Back on the wife's machine just now.

 

[frover2000]

Im thinking it's a heat problem, make sure the heatsink and fan is installed properly on the cpu also add a case fan if possible

 

[Felecha]

Weird. Called a friend who's built a couple. He thought I might be losing power if something was grounding out and shorting, rather than something breaking a hot connection. He suggested taking off the other panel, to look behind where the motherboard screws to the inner frame panel there. Maybe something tiny fell in there and was touching something the wrong way? Nothing to lose.

As soon as I removed the first of the two screws, it fired up, all the way through the boot. I removed the panel completely, so both panels are now off, and now I can't seem to get it to die no matter what I do in the way of moving and wiggling it. Not that I'm getting rough with it at all, but I've tilted it, wiggled it, flexed it, and where it used to be "fragile", and would shut down if I touched it the wrong way, now it seems fine.

What in the world?

 

[Fardringle]

Sounds like something on the 'back' panel is shorting out the power circuit. Look closely to see if any exposed wires (or maybe part of the power supply itself) or part of the motherboard is able to physically touch that panel. If so, try moving things to make it so they can't touch the panel, or if the can't be moved then use some judicious application of electrical tape to insulate the offending parts/wires.

 

[Felecha]

I thought of just that and looked all over. Nothing in there to touch, at all. I'm baffled

 

[twong82]

I had the problem when my computer would just shut off by itself randomly and I found out that it was a bad power supply. I replaced it and everything was fine.

 

[Rand]

Usually problems like that are related to underpowered PowerSupplies.

 

[Felecha]

300Watts on mine not enough? And it would run fine for 3 months and then start showing problems with underpower?

 

[Avatar26]

Sounds like a short, make sure you don't have a bare wire touching the case somewhere...

 

[Felecha]

Stayed on all night after I took the second panel off. That is, the computer stayed on, I went to bed.

Decided just now to do the simplest of tests -- put them back on and see. Back on, boot right up.

I did look all around for possibilities, couldn't see any potential shorts. Eveything is coated wire from one end to the other, plastic plug covers, nothing stripped and screwed down that might be loose.

 

[Felecha]

Could this be an idea that would point somewhere?

All those times that it died just after the initial beep -- I understand there's something in the boot sequence that starts out with a Power-On-Self-Test, ended by the beep. Would it be, then, that only after it passes the POST does the power go out to other things, and the problem was there, ready to short out and kill it but wouldn't short until the power got there ater the POST? If that's a reasonable line of thinking, then what component first gets its power about one second after the beep? That might lead me where to look for a problem.

 

[Felecha]

Well, curiouser and curiouser.

I decided to take another look behind the second panel. When I had it open, there was only one wire visible, leading up to the top of the box. I realized that's got to be the wire to the switch. So I shut down, normal shutdown using Start/ShutDown, pulled the plug, pulled the cover, and sure enough, I saw a small indent in the vinyl cover of the white wire of the two wires, one black, one white. I examined it closely and saw the indent perfectly matches with the business end of whatever plastic mounting screw holds the plastic front face of the case onto the main steel frame inside, about halfway down. When the panel was put on, that white wire, which I presume is the ground, following black/white convention, got pinched between one of the tabs on the edge of the panel, that snugs it into the case, and that screw. The screw is plastic, and ends in what looks like the tip of a Philips screwdriver. The indent doesn't look real serious, and doesn't seem to have actually cut the cover of the wire, but it's a definite dent.

I pulled the wire well out of the way and put the cover back on, plugged her in, and started to slide it back under the desk, and .... it turned on by itself!!

Now, mind you, the last time I shut down I did it normally, through Windows. In all my years, that always meant you hit the switch to turn it on again. This time it came on again just as if it were recovering from one of its random self-inflicted short-out shutdowns.

This is really strange now, and it's definitely off to the shop with it today.

 

[Degenerate]

i think its the power

 

[moocat]

You could try unplugging the power switch wires from the motherboard and just turning it on/off by shorting those two pins with a piece of wire (this is for troubleshooting of course, not a solution to the problem). It's possible that your switch, or the wires from the switch to the motherboard are faulty.

I had a computer that would restart itself after shutdown. It would run all day but as soon as you powered it down it would turn itself back on. I could turn in on/off using the method described above and it behaved normally.

 

[Felecha]

I took it to the guy who built it and he agreed it was highly likely to be the pinched spot on the power switch ground wire. He also found, as I did, that now that it's no longer pinched he couldn't get it to spontaneously shut down no matter what he did. So he taped over the pinch spot, re-routed the wires so they couldn't get pinched again, and I took it back for now. It's an InWin full tower, not a box he keeps in stock, and if he took it till he could get a new switch sent, I'd be SOL for a while. He suggested he could move everything into another case, wheich he did have available, and if the wire was the problem, that would do it, but the other case was nowhere near as good for my purposes. So I agreed the thing to do was to come home with it and pray, and he will order a switch and keep it for me in case it ever happens again. If not, it won't bother me much to know that it's lurking there.

He also agreed if the pinch spot is actually damaged inside the vinyl, I could always cut it out and butt-splice a repair. I've done that lots of times on car wiring.

So, I think I'm OK.

Thanks for the inputs

F