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cyberdome
30th December 2014, 04:19 AM
Hi everone,

I have been running Fedora on my desktop machine and recently, It has been rebooting on its own. I need guidance as which log files, where can I look for errors?

There has to some errors I can look at to investigate the issue.

Thanks for any help.

take care :)

Happy New Year!!! :)


Computer Details -

Running Fedora 20

running VMware Ubuntu, OpenSUSE, and Windows 8.

flyingfsck
30th December 2014, 06:58 AM
There may be something in a log file, but usually a sudden reboot is just that - sudden. More often than not it is due to bad power quality. If it was me, I would check the motherboard for expanded capacitors and replace the power supply with one from my junk box to narrow it down.

rbmorse
30th December 2014, 06:20 PM
Is this a desktop or a laptop?

Does the rebooting occur in all the operating systems on the machine, or just Fedora?

To amplify on Flying's comment:

If the machine is a desktop PC, the capacitors in question are most likely in the voltage regulator circuits in the general vicinity of the CPU and inside the power supply. The capacitors look little beer cans and may be wearing a vinyl jacket. They will be of various sizes, from about 5mm tall and larger. The sides should be straight and tops flat to slightly concave. If the sides or tops are bowed out or there is evidence of leakage (brown goo or white crystalline "feathers" around the capacitors) then it is likely the components have suffered internal degradation and may periodically short circuit which leads to a spontaneous reboot. This is most likely to become a problem on a "budget" brand motherboard that has been in service for two or three years or longer. In any case, if one capacitor appears to be "bad" the motherboard should be removed from service. If one is failed it is quite likely others are suffering the same problem but have yet to manifest symptoms. It is not cost effective to replace the capacitors individually.

The same is true for the capacitors inside the power supply, but these will be harder to examine both because the PSU is enclosed in a cage, and the propensity for manufacturers to liberally spread mastic (i.e., glue) around the inside to keep things together and damp internal oscillations that cause objectionable noises. Again, this is more likely to be a problem of a computer that was purchased primarily due to its low price and has been in service for a period of time.

cyberdome
31st December 2014, 04:22 AM
There may be something in a log file, but usually a sudden reboot is just that - sudden. More often than not it is due to bad power quality. If it was me, I would check the motherboard for expanded capacitors and replace the power supply with one from my junk box to narrow it down.

Yes, I am thinking more of a power issue as well.

---------- Post added at 10:22 PM ---------- Previous post was at 10:20 PM ----------


Is this a desktop or a laptop?

Does the rebooting occur in all the operating systems on the machine, or just Fedora?

To amplify on Flying's comment:

If the machine is a desktop PC, the capacitors in question are most likely in the voltage regulator circuits in the general vicinity of the CPU and inside the power supply. The capacitors look little beer cans and may be wearing a vinyl jacket. They will be of various sizes, from about 5mm tall and larger. The sides should be straight and tops flat to slightly concave. If the sides or tops are bowed out or there is evidence of leakage (brown goo or white crystalline "feathers" around the capacitors) then it is likely the components have suffered internal degradation and may periodically short circuit which leads to a spontaneous reboot. This is most likely to become a problem on a "budget" brand motherboard that has been in service for two or three years or longer. In any case, if one capacitor appears to be "bad" the motherboard should be removed from service. If one is failed it is quite likely others are suffering the same problem but have yet to manifest symptoms. It is not cost effective to replace the capacitors individually.

The same is true for the capacitors inside the power supply, but these will be harder to examine both because the PSU is enclosed in a cage, and the propensity for manufacturers to liberally spread mastic (i.e., glue) around the inside to keep things together and damp internal oscillations that cause objectionable noises. Again, this is more likely to be a problem of a computer that was purchased primarily due to its low price and has been in service for a period of time.


thanks for your response. YES, it is a desktop PC. It is just main OS Fedora which is rebooting without any indication. I used the LAST command but no errors, nothing in log files to indicate any issue.

Yes, I think you are correct it might be a power issue. I am going to clean up the desktop from inside out. because I have not cleaned this desktop PC for a long long time.

take care :)
HAPPY NEW YEAR

rbmorse
31st December 2014, 06:01 AM
The part where the problem only manifests under Fedora is vexing. By all means open the box and clean it out. Inspect the caps while you're there. You might find a hand magnifier and bright light useful. Also might want to change the battery..those things don't last forever.