9.0 spontaneously reboots

Matthew Seaman matthew at FreeBSD.org
Mon Mar 12 16:57:11 UTC 2012

On 12/03/2012 14:07, Volodymyr Kostyrko wrote:
> What should I blame now? Is it some programming error or should I
> continue with testing/changing motherboard and cpu?

Instability that appears spontaneously (and especially if it persists
across system updates) is almost always caused by hardware problems.
So, yes, carry on swapping out components until you can isolate where
the problem is.

Some common hardware problems which might result in the problems you've

   * PSU going flakey.  If you have the right measuring equipment, this
     is pretty easy to detect by looking at the output voltages -- if
     they've drifted out of spec, or if you've got mains frequency
     jitter leaking through then its no wonder your system crashes.

   * Similarly, if the crashing is associated with system load,
     (particularly at startup, when things are happening like disks
     spinning up) this can indicate a power supply fading under load.
     That can happen due to age, or because you've been adding extra
     hardware and haven't considered the power requirements.

   * The other reason for crashing under load is overheating.
     Sometimes this can be cured easily by cleaning dust out of vents
     and heat-sinks.  Check too for fans either seized or running

   * You may need to clean off any old heat-sink compound and re-apply
     a fresh layer, especially if you've taken CPU coolers off at
     some point.

   * There's also the old capacitor problem: electrolytic capacitors
     have a failure mode that generates some positive pressure inside
     them.  This is detectable by the end of the capacitor being bowed
     out, rather than slightly concave. (Generally this means a new
     motherboard, although I've heard of people being able to solder in
     replacements successfully.)

Other than that, try disconnecting and reconnecting peripherals like
disks or DVDs and so forth in various combinations to test if that
improves system stability.  One faulty component can knock the whole
machine over.



Dr Matthew J Seaman MA, D.Phil.
PGP: http://www.infracaninophile.co.uk/pgpkey

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