Am Samstag 30 September 2006 14:16 schrieb reader@newsguy.com:
> Group, I recently built a ventilated stucture around my 4 desktops to
> try to quiet things down and get rid of the heat.
>
> I made no provision for forced shutdown in case of overheat, which is
> quite likely to happen if, for example the main ventilation fan went
> down for some reason.
>
> Well, that happened due to stupidity on my part with getting used to
> the new setup.  I fired up a computer and neglected to turn the fan
> on.  Then left it running overnight.
>
> Well, given the confined space and very little/no ventilation (of my
> homemade structure) the computer got hot...
>
> Sometime this morning I see syslog messages written to tty that say:
>
>   Message from syslogd@reader at Sat Sep 30 04:41:32 2006 ...
>   reader kernel: CPU0: Temperature above threshold
>
>   Message from syslogd@reader at Sat Sep 30 04:41:32 2006 ...
>   reader kernel: CPU0: Running in modulated clock mode
>
> [...]
>
> Some kind of attempt by kernel to cool things down.  But will it
> actually shutdown if it gets dangerously hot?
>
> Further, how can I discover what temperatures were involved when this
> happened?
>
> Or can I set something to make a shutdown happen at a specific
> temperature?
>
> A nicer solution would be somekind of added stand alone temperature
> monitor in the enclosure that causes a controlled shutdown like one
> gets with `shutdown -h now'.
>
> Anyone here with some experience in this kind of thing that can steer me
> to some good information?

Just have a look to your trip_point:

mgisbers@mars ~ $ cat /proc/acpi/thermal_zone/THRM/trip_points
critical (S5):           95 C
passive:                 87 C: tc1=1 tc2=5 tsp=10 devices=0xdff72dc4

When reaching 95° my computer starts to shutdown fast.

I found more Information on 
http://acpi.sourceforge.net/documentation/thermal.html

Maybe it helps you too.
-- 
 Michael Gisbers
 http://www.lugor.de