Re: CPU burns 3

[Helge Hafting <helge.hafting@aitel.hist.no>]

antonio giulio wrote:

> Hi,
>
> any weeks ago, I have posted about a strange behaviour of my amd64
> cpu. GPG or molecular dynamics calcs in 3/4 minutes make cpu burning.
> Now notebook is at acer labs to control (under garantee). A technician
> (at phone) tell me that his stress-cpu program (windows) have found
> nothing (3-days running normally and again continue, however notebook
> come back in the next week). And so, could be a problem linux
> related?!?!?!?!? Ok, it's impossible that software damages hardware...
>
>  
Actually, sw can damage hw these days.  Some motherboards,
particularly portables, have fans where the speed is controlled
by the cpu.   (So they can slow down for silent running at times
of low load.)
If you deliberately programs the fans to stop, then
the cpu will overheat and break.  The same goes for any other
cooling/power consumption feature under cpu control.  An ill-designed
board could theoretically have cooling that need a correct driver to 
_start_,
but I guess all sane designs start the fans at full speed and only need
a driver for the optional slowdown.

I am sure you didn't do anything like that, but it is just the sort of 
thing a
virus writer might do.  Other possibilities for sw destroying hardware:

* Some old crt monitors let you stop the electron beam if you
  program the screen update frequencies out of spec.  That will
  quickly burn out the screen in that spot. 
  (That pixel get 640x480=307200 times the normal energy . . .)
  There are few of  those around - but see documentation for X
  modelines for details.

* Most boards have a programmable bios these days, so you can download
  updates.  Program something non-executable, and the machine
  won't be able to boot anymore.  Technically not destroyed, but you'll
  have to remove the chip and have it reprogrammed out of the pc.
  Most people don't have the necessary equipment and will have to pay.
  It might also be near impossible if the chip is soldered to the board. 

> Have you any idea for other tests or what looking for?
>  
Surey the service people can download a linux live CD (64-bit, of course)
and run GPG for a few hours in a room/enclosure as hot as the pc spec 
allows.
If it happens with a live linux cd from one of the well-known distributors,
then they can't claim that you had a "bad" linux setup.

Helge Hafting