random shut downs. please help.

[Heat]

Hey guys, been too long. I am really stumped with this one. Sorry about the many details.

Problem:
The computer shuts down randomly and suddenly. Sometimes, it doesn't want to come on at all, yet it sometimes even turns itself on. Shutdowns happen in bios, mid-way thru windows startup, or when windows is running. It still may work fine for a few hours or just shut down after 10 minutes of uptime.

Setup:
This is a dell vostro 200 minitower (yeah I know). Worked perfect for 2.5 years until the last couple of weeks.
- 2 gb ram (2 1 gb sticks).
- intel dual cpu E2140 @ 1.60ghz.
- onboard lan/audio/vga.
- win xp pro sp3.

What I already tried:
1. cleaned dust out of case.
2. cleared cmos.
3. unplugged and re-inserted all wiring.
4. updated bios to latest.
5. turned off remote/wake on LAN and auto power on in bios. Also turned off wake on lan via device manager.
6. ran memtest+ v4.0 and got no errors.
7. tried computer with other outlets and still same problem.
8. checked fans, back fan and cpu fan seem to be fine.
9. event viewer shows no errors and hard drive seems fine.
10. MSE says no viruses.

Temps seem OK - 35C. Don't do any gaming.

Not sure about voltages:
vcore1: 1.18V
vcore2: 3.04V
+3.3V: 3.31V
+5V: 5.08V
+12V: 12.10V

-12V: -16.64V
-5V: -8.48V
-5V: -4.97V
Vbat: 3.07V

Possible external factors:
I did turn on the AC after it was off all winter and this seems to be when the problem started to happen, but I haven't noticed other electronics having problems - tvs work fine, house lights don't blink etc.

I don't have a spare psu or mobo to try out. So you guys think the mobo or psu is going bad? Computer is maybe just getting old and flaky?
Thnaks for reading!

 

[Bobnova]

Find yourself a voltmeter, Garbor Freight usually has 'em for $2-$7, and use that to check the 12v/5v/3.3v lines. Software is dubious at best.


What are your cpu temps like at idle and prime95 load?

 

[TechWizard]

Sounds to me like the system is unstable. Either the power supply or the motherboard in my opinion. I've been working in a computer repair shop for about half a year (yes I know that isn't very long at all, but I've seen a fair share of issues like this) and I'd have to say 95% of the time we have an issue like this it is one of the two.

If your PSU's voltages seem fine then I'd have to say it's probably the motherboard.

What brand is the motherboard? Are any of the capacitors on the motherboard bulging
outward? (Image incase you don't know what I'm talking about)

http://www.tnpcnewsletter.com/dan/Bulging_Capacitors/close-up.jpg

Edit: Relevent, but probaby not the issue. I actually had a computer that would randomly restart/refuse to boot up when I had my cell phone plugged into it. It's possible, but UNLIKLY that a usb device is causing the issue. But still possible if you've really tried everything and need a last resort. Sometimes USB ports get overvolted because of bad devices and can short out your motherboard/cause an unstable system.

 

[newbski]

We had a server do this and what ended up happening was the back covers for the PCI-X slots fell and was touching the mobo.

Something this simple can cause a machine to reboot.

I agree with a power suply/mobo issue. Check all cables and replug in the mobo cable perhaps and if you have canned air I always blow it in a PSU that's a few years old might help.

 

[Heat]

OK. Thanks for the replies. I'll open up the case later and check the capacitors and look into a voltmeter.

I first noticed the problem when the pc failed to wake up from hibernation and restarted. So hibernation is disabled now. There's been no reboots or BSODs, just shutdowns.

Guess it is almost time for a new pc, and can look into replacing the psu/mobo later.

 

[SFLC2000]

Sounds to me like the system is unstable. Either the power supply or the motherboard in my opinion. I've been working in a computer repair shop for about half a year (yes I know that isn't very long at all, but I've seen a fair share of issues like this) and I'd have to say 95% of the time we have an issue like this it is one of the two.

If your PSU's voltages seem fine then I'd have to say it's probably the motherboard.

What brand is the motherboard? Are any of the capacitors on the motherboard bulging
outward? (Image incase you don't know what I'm talking about)

http://www.tnpcnewsletter.com/dan/Bulging_Capacitors/close-up.jpg

Edit: Relevent, but probaby not the issue. I actually had a computer that would randomly restart/refuse to boot up when I had my cell phone plugged into it. It's possible, but UNLIKLY that a usb device is causing the issue. But still possible if you've really tried everything and need a last resort. Sometimes USB ports get overvolted because of bad devices and can short out your motherboard/cause an unstable system.

Hey, Rookie! EXCELLENT JOB! I've been in the computer industry since mid-80's and thought my issue was overheating on my Vostro 200 - I leave the side of the case off, so was easy to use a magnifying glass and LED flashlight to look at the capacitors, and, well, yep, found the culprit! Leaking capacitor! Thank you for the JPEG in your post and taking the time to put your info on this forum so many years ago!

 

[RJARRRPCGP]

Hey, Rookie! EXCELLENT JOB! I've been in the computer industry since mid-80's and thought my issue was overheating on my Vostro 200 - I leave the side of the case off, so was easy to use a magnifying glass and LED flashlight to look at the capacitors, and, well, yep, found the culprit! Leaking capacitor! Thank you for the JPEG in your post and taking the time to put your info on this forum so many years ago!

Please go to here:

http://badcaps.net