Debugging bad memory problems

[Valeri Galtsev]

On Mon, April 27, 2015 8:56 am, Dave B wrote:
> On 26 Apr 2015 at 23:05, Fernando Apesteguía wrote:
>
>> I booted from a memtest CD-ROM. It passed a couple of tests fine and
>> then it rebooted while doing a "bit fade" test at around 93%.
>> Removing the modules is tricky since this laptop has screws all
>> around in dark corners (even removing the battery needs a screw
>> driver). I will try to limit physical memory with hw.physmem and see
>> if it makes any difference.
>>
>> Thanks!
>>
>
> Check for CPU cooling problems too, such as an obstructed cooler or
> grumbly
> fan.  (Also if you can, check for bad power supply issues.)
>
> Older AMD CPU's don't take kindly at all to running too hot, unlike some
> Intel
> devices that will start to cycle skipping to lower the disipation, just
> slowing down
> in effect.

AMD might have been slightly behind Intel on this one: stepping down the
clock (or diminishing clock multiplier to be more precise - "power now"
they called the feature related to effectively changing the CPU speed).
However, as far as I know, AMD chips were always more robust than Intel
ones. You can boil water on it, and it still will keep running without
glitches - as someone once put it.

I do agree with your advice make sure the heat sink in not clogged: even
though you will need more effort to heat AMD CPU to start on the chip
memory controller failing compared to Intel CPU, still it well may be the
snag.

Valeri

>
> "Supliment the cooling" when running such tests, RAM can disipate quite a
> bit of
> power when worked hard (as Memtest86 does.)   Elevate the laptop and waft
> air
> under it, but not in such a way as to oppose it's own intended airflow.
>
> Hope you find the trouble.
>
> Dave B.
>
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++++++++++++++++++++++++++++++++++++++++
Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247
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