RE: Linux crashed a lot - more info
> From: John Reinke [mailto:jmreinke@falcon.cc.ukans.edu]
>
> On Fri, 1 Sep 2000, Larry Elmore wrote:
>
> > Did you try replacing the power supply? This sounds suspiciously like an
> > almost-good power supply. That is one item that one should
> _never_ skimp on,
> > but a lot of low-end clones do to save a few bucks. Of course,
> there's other
> > possible causes. My wife's machine got to be like that, and after some
> > poking about, I discovered that the CPU fan was going bad -- it
> was turning,
> > but not quite fast enough _some_ of the time. Sometimes it'd run at full
> > speed for a couple of days before slowing down, sometimes a few
> minutes, and
> > sometimes would start off slow in which case the machine
> sometimes wouldn't
> > even finish booting before the CPU overheated. Intermittent
> problems like
> > that can be really difficult to track down sometimes.
>
> No, the only spare box I have has an old AT power supply.
>
> Yet another problem I've had that you reminded me of - the CPU fan will
> occasionally speed up and slow down. I've seen it stop almost completely,
> too. Sometimes, it makes a nasty rattling sound, but it seems to be
> attached well enough to the CPU that it shouldn't fall off. I've seen that
> the BIOS knows what speed the CPU fan is turning - is that how the fan can
> affect the computer? I've never seen the CPU get too hot.
I don't know if the fan should be variable speed or not. It seems awfully
silly to me to add the complexity of a thermostat and additional code in the
BIOS so you can save probably 0.1 cents worth of electricity per month by
slowing that tiny CPU fan down when the chip is cool, but I seem to remember
reading something about such nonsense a few months ago. If that fan is
making a rattling or buzzing noise sometimes, I'd bet that the fan's on its
last legs. When I took the fan off the CPU in my wife's machine, when it
slowed down, you could really feel the difference when you were holding it
in your hand -- lots of vibration. It made a low pitched buzzing noise when
it went slow while attached to the CPU because the motherboard and case
acted like a soundboard of a string instrument and amplified the vibration's
sound.
I'd suggest trying to find out whether the CPU fan speed is supposed to be
controlled by the BIOS, and if it's not, there's your culprit. If the BIOS
does control the speed, I'd still suspect the fan because of the noise you
describe. Luckily, they're relatively cheap. If a different fan does the
same thing, and the BIOS doesn't control fan speed, that'd indicate a bad
power supply or maybe a bad connection to the power supply. Check the
voltage going to the fan with a meter, if you've got one. Other than that, I
don't know what else to suggest. I hope this helps!
If the CPU is overheating just a little bit (i.e., the fan is running but
sometimes slowly), the symptoms can be fairly random. Sometimes my wife's
machine would just lock up and freeze, other times it would reset and reboot
without warning, a few times Windows just started acting weird and I don't
know whether that was the computer or Windows at fault there. :)
I suppose if it ever overheated too much, it might permanently damage the
chip and it wouldn't necessarily be totally non-functional afterwards. I
just remembered having that happen once (I think) on an old 486 when the fan
just completely quit. After trying to reboot a few times and having it lock
up after a couple of minutes each time, I opened up the case and discovered
the problem. I replaced the fan, but the machine was too unreliable to use
after that. It sometimes would run for hours just fine, other times only a
minute or two. Certain programs were guaranteed to lock it up -- I suspect
there were just a few opcodes (maybe only one) that were failing, but
eventually it brought down the machine. I never tried replacing the CPU
because 486's weren't really being sold anymore and I could get a whole new
486 box (for a firewall) for $20 a whole lot easier.
> I'm really starting to doubt my hardware now. ...all I want is a happy
> Linux box that never crashes... Perhaps I should perch a stuffed penguin
> on top of it.
Couldn't hurt! ;-)
Larry
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