Diagnosing reboot under load
xfb52 at dial.pipex.com
Mon Nov 7 19:03:31 GMT 2005
> I'm really beginning to doubt it's the PSU. Why? I cannot get the
> output voltage to drop no matter what load I throw at it. I plugged
> in four additional hard drives and ran a system stress test and still
> the voltages remained rock steady at the values I stated earlier. I
> ran it for an hours with the high-low monitor on a Fluke multimeter.
> The +5 stayed near 5.1 with 5.08 as the bottom, and the +12 stayed
> near 11.89 with 11.84 as the minimum. I even had one of the "random
> segfaults" and the +12 voltage never dropped below 11.84. I'm not
> sure how I can get the load any higher without using resistors which
> most certainly does not simulate the load I'm generating while compiling.
> That leaves memory, CPU or mobo. I ran memtest86+ and it reported no
> errors. I'll run it again for an extended period of time while I'm at
> school to see if it reports anything. That leaves CPU and mobo.
> Anyone got any ideas how to test those? The only system test I can
> run that does report an error is Lucifer 1.0 (on the ultimate boot
> cd). The mprime test and cpuburn do not find any errors.
The usual advice is to run memtest86 overnight, but I'm not convinced it
will find a fault related to either temperature or load, since memtest
seems to cause neither. Still, worth a try.
When I was arsing around with overclocking, I could reliably crash the
machine (IIRC) like this:
run cpu burn
run mprime (or was it a pi generator? can't recall now...)
wait for temp to hit max
wait < 5 mins for either machine to crash or prime/pi test to have error
I was fairly convinced at the time that it was the memory which didn't
cope. This is possibly not far off what happens in a big series of
As for diagnosing faults, you may be down to replacing components one at
a time and seeing if it makes a difference. That's easier when the
machine crashes quickly, so if you can find something which reliably
crashes it, that's good. If you have >1 memory stick and the machine
will run with a single stick, try each stick in turn. You could also
try deliberately under-performing the memory and see if that makes it
reliable. Was the memory you go on the compatibility list for the mobo?
Hope that helps,
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