Intermittent reboots. WTF?!?
February 18, 2008 2:24 PM Subscribe
Why is my mother-in-law's computer rebooting?
My mother-in-law's computer (generic Sempron) spontaneously reboots. Sometimes it restarts after 1 hour, sometimes 8 hours, but even if it is sitting idle it will reboot. A fresh install of Windows can last up to 24 hours without rebooting. Installing the anti-virus software (I've tried several) makes the problem much worse. I think I've ruled out heat as an issue, because I ran it outside and the problem persisted. I've also determined that its a hardware problem, because Puppy Linux also spontaneously reboots, although it takes 24 to 48 hours for the problem to occur running Linux. (FWIW, Ubuntu hangs while loading and can't run.) Which part (e.g. power supply, RAM, moboard, etc.) is most likely to be the culprit? The computer has an inexpensive motherboard with all functions (video, sound, network) on board, 1 gb RAM, Sempron with stock fan, generic power supply.
My mother-in-law's computer (generic Sempron) spontaneously reboots. Sometimes it restarts after 1 hour, sometimes 8 hours, but even if it is sitting idle it will reboot. A fresh install of Windows can last up to 24 hours without rebooting. Installing the anti-virus software (I've tried several) makes the problem much worse. I think I've ruled out heat as an issue, because I ran it outside and the problem persisted. I've also determined that its a hardware problem, because Puppy Linux also spontaneously reboots, although it takes 24 to 48 hours for the problem to occur running Linux. (FWIW, Ubuntu hangs while loading and can't run.) Which part (e.g. power supply, RAM, moboard, etc.) is most likely to be the culprit? The computer has an inexpensive motherboard with all functions (video, sound, network) on board, 1 gb RAM, Sempron with stock fan, generic power supply.
I'd look at the power supply first.
I have had an experience, however, with a computer that developed a faulty power-on switch that produced similar symptoms. As you might imagine, this was maddening to diagnose. Try disconnecting the case power button from the motherboard after you have it booted up...
posted by mr_roboto at 2:36 PM on February 18, 2008
I have had an experience, however, with a computer that developed a faulty power-on switch that produced similar symptoms. As you might imagine, this was maddening to diagnose. Try disconnecting the case power button from the motherboard after you have it booted up...
posted by mr_roboto at 2:36 PM on February 18, 2008
Probabilities, in order:
-heat. Yea, youtook it outside. Did you pull off the heatsink and put more goo on the chip after cleaning it with alcohol? Did you dust between the sticks of ram?
-RAM bad stick or poorly seated, but more likely a bad stick. Try pulling 1 stick at a time and see if the problem persists
-Check jumpers and PSU-I'm not feeling PSU on this one, I'm feeling another issue. Make sure jumpers are all seated and the PSU is super plugged in. You can snag another cheap PSU on newegg for ~$12. Don't listen to people who say you need a more expensive one, this computer does not warrant that.
-Faulty MoBo--rare, but it happens.
I thought I had a system with the 4th case there, a bad MoBo. I put in a brand new thermaltake heatsink and lots of other things and the problem persisted. I took out the chip, cleaned the top with rubbing alcohol and a qtip, put on some thermal paste, and fired it back up. No reboots or BSOD's since.
(I also now run it with the side off...but that's a different story.)
posted by TomMelee at 2:43 PM on February 18, 2008
-heat. Yea, youtook it outside. Did you pull off the heatsink and put more goo on the chip after cleaning it with alcohol? Did you dust between the sticks of ram?
-RAM bad stick or poorly seated, but more likely a bad stick. Try pulling 1 stick at a time and see if the problem persists
-Check jumpers and PSU-I'm not feeling PSU on this one, I'm feeling another issue. Make sure jumpers are all seated and the PSU is super plugged in. You can snag another cheap PSU on newegg for ~$12. Don't listen to people who say you need a more expensive one, this computer does not warrant that.
-Faulty MoBo--rare, but it happens.
I thought I had a system with the 4th case there, a bad MoBo. I put in a brand new thermaltake heatsink and lots of other things and the problem persisted. I took out the chip, cleaned the top with rubbing alcohol and a qtip, put on some thermal paste, and fired it back up. No reboots or BSOD's since.
(I also now run it with the side off...but that's a different story.)
posted by TomMelee at 2:43 PM on February 18, 2008
When I had a problem like this it was bad RAM. Try running Memtest86 overnight to see if finds any problems. Good luck.
posted by stopgap at 2:47 PM on February 18, 2008
posted by stopgap at 2:47 PM on February 18, 2008
Best answer: Bad capacitors.
There are tons of these out there. Check the capacitors for oozing capacitor goo and if there's even one bad one, there you go.
I can't tell you how many systems I've seen this happen to - dozens of 2004-06'ish mobos.
posted by bhance at 2:56 PM on February 18, 2008 [2 favorites]
There are tons of these out there. Check the capacitors for oozing capacitor goo and if there's even one bad one, there you go.
I can't tell you how many systems I've seen this happen to - dozens of 2004-06'ish mobos.
posted by bhance at 2:56 PM on February 18, 2008 [2 favorites]
Seconding bhance, it sounds like the classic behavior of bad capacitors.
posted by samsara at 6:22 PM on February 18, 2008
posted by samsara at 6:22 PM on February 18, 2008
Most likely to least likely:
Bad power supply
Bad capacitors
Bad RAM
Something else
posted by flabdablet at 6:28 PM on February 18, 2008
Bad power supply
Bad capacitors
Bad RAM
Something else
posted by flabdablet at 6:28 PM on February 18, 2008
I once had a situation at a job where my PC would do the same thing...just spontaneously reboot itself. It wasn't clockwork regular, but it was often enough to be maddening.
We eventually tracked the problem down to the office copier that was on the same electrical circuit as my PC. The copier would go into standby-mode when not working. Then, when it powered-up to run a print job, it would cause just enough of a draw on the circuit to cause my PC to reboot.
Now, obviously your MIL doesn't have an office copier in her home. But, you might check to see if there isn't something on that circuit that causes such a sudden draw. An old refrigerator? The furnace?
And the bad capacitors, too.
posted by Thorzdad at 6:54 PM on February 18, 2008
We eventually tracked the problem down to the office copier that was on the same electrical circuit as my PC. The copier would go into standby-mode when not working. Then, when it powered-up to run a print job, it would cause just enough of a draw on the circuit to cause my PC to reboot.
Now, obviously your MIL doesn't have an office copier in her home. But, you might check to see if there isn't something on that circuit that causes such a sudden draw. An old refrigerator? The furnace?
And the bad capacitors, too.
posted by Thorzdad at 6:54 PM on February 18, 2008
The words "inexpensive motherboard" immediately made bad capacitors jump to mind. I doubt it's a PSU issue - those manifest themselves on boot or under heavy load. I doublt it's electrical issues, since you've tried it outside (presumably on a different circuit).
Anything else is pretty much fair game. Computers can be maddening to fix.
posted by wsp at 7:32 PM on February 18, 2008
Anything else is pretty much fair game. Computers can be maddening to fix.
posted by wsp at 7:32 PM on February 18, 2008
Response by poster: On close inspection, I found a single bad capacitor with electrolyte leaking from the bottom. I never would have suspected this. Thanks to all for saving me some cash!
posted by Crotalus at 7:57 PM on February 18, 2008
posted by Crotalus at 7:57 PM on February 18, 2008
Bad capacitors travel in packs. It's always the the high-capacitance, low-voltage, low-equivalent-series-resistance capacitors that fail, and mobos usually have about eight of the same kind of these. If you currently believe that only one of them is bad, take a good close look at the others. I'd bet money that if one has actually blown its rubber seal out of the bottom, the others will at least have bulging tops.
If you're going to replace a 2200μF 10V mobo capacitor (a fairly typical rating) yourself, you should probably replace all eight. Don't just rush out to Radio Shack and buy the first 2200μF 10V electrolytic capacitors you see, because they won't work. You need low-ESR, high-temperature types.
I've had good results using Rubycon ZL series and Nichicon UHD series parts. The actual capacitance rating is not that critical in this application - buy replacement parts that have the same voltage rating or higher, the same case diameter and lead pitch (so they will physically fit where the old ones did) and the highest ripple current rating and lowest impedance at 100kHz that you can find.
For example, a 1500μF 10V Rubycon cap, with its rated ripple current of over 2 amps and an impedance at 100kHz of 22mΩ, will generally be a satisfactory replacement for a leaky 2200μF 10V Taiwanese cap if the physically larger 2200μF Rubycon parts won't fit in your mobo.
You also need to be quite careful when removing the old capacitors. It really helps to use a good power desolderer, if you can get access to one. Doing it with a standard soldering iron and one of those spring-loaded suckers, or with solder wick, or by heating both joints at once and easing the cap out of the board as the solder melts - I have made all these methods work, but I've also ruined the odd mobo. It's pretty easy to rip the through-hole plating out of the mobo if you're not careful, and since these caps are generally connected to power planes, ripping out the through-holes can completely wreck a board. Many fairly recent motherboards are also built with lead-free or low-lead solder, which melts at a higher temperature than ordinary lead solder and is therefore harder to remove with standard tools.
If you're not doing it yourself, it will almost certainly be cheaper just to get a replacement mobo.
posted by flabdablet at 12:49 AM on February 19, 2008
If you're going to replace a 2200μF 10V mobo capacitor (a fairly typical rating) yourself, you should probably replace all eight. Don't just rush out to Radio Shack and buy the first 2200μF 10V electrolytic capacitors you see, because they won't work. You need low-ESR, high-temperature types.
I've had good results using Rubycon ZL series and Nichicon UHD series parts. The actual capacitance rating is not that critical in this application - buy replacement parts that have the same voltage rating or higher, the same case diameter and lead pitch (so they will physically fit where the old ones did) and the highest ripple current rating and lowest impedance at 100kHz that you can find.
For example, a 1500μF 10V Rubycon cap, with its rated ripple current of over 2 amps and an impedance at 100kHz of 22mΩ, will generally be a satisfactory replacement for a leaky 2200μF 10V Taiwanese cap if the physically larger 2200μF Rubycon parts won't fit in your mobo.
You also need to be quite careful when removing the old capacitors. It really helps to use a good power desolderer, if you can get access to one. Doing it with a standard soldering iron and one of those spring-loaded suckers, or with solder wick, or by heating both joints at once and easing the cap out of the board as the solder melts - I have made all these methods work, but I've also ruined the odd mobo. It's pretty easy to rip the through-hole plating out of the mobo if you're not careful, and since these caps are generally connected to power planes, ripping out the through-holes can completely wreck a board. Many fairly recent motherboards are also built with lead-free or low-lead solder, which melts at a higher temperature than ordinary lead solder and is therefore harder to remove with standard tools.
If you're not doing it yourself, it will almost certainly be cheaper just to get a replacement mobo.
posted by flabdablet at 12:49 AM on February 19, 2008
2nding flabdablet's 'just replace the mobo'. You didn't say if this was storebought or a homebuild but consider calling the computer or mobo. vendor and politely asking for a new one. They may replace it out of good faith.
I deal with a major PC vendor whose GX2** line was so riddled with bad caps that they're still replacing motherboards even though they're out of warranty. I very much give them props for this, and it has set land-speed records for technical support calls:
Them: "Let's diagnose the problem: What OS are you using? XP? Vista?"
Me: "There's caustic black poo coming out of the capacitors."
Them: "New motherboard's in the mail."
posted by bhance at 7:02 AM on February 19, 2008
I deal with a major PC vendor whose GX2** line was so riddled with bad caps that they're still replacing motherboards even though they're out of warranty. I very much give them props for this, and it has set land-speed records for technical support calls:
Them: "Let's diagnose the problem: What OS are you using? XP? Vista?"
Me: "There's caustic black poo coming out of the capacitors."
Them: "New motherboard's in the mail."
posted by bhance at 7:02 AM on February 19, 2008
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posted by The Light Fantastic at 2:29 PM on February 18, 2008