Prestigio Nobile 157 ACPI - overheating

Nate Lawson nate at
Mon Oct 1 12:10:20 PDT 2007

Kevin Oberman wrote:
>> From: Milan Bartos <merlyn500 at>
>> Date: Mon, 1 Oct 2007 19:03:15 +0200
>> Sender: owner-freebsd-acpi at
>> Hi. I have laptop Prestigio Nobile 157 and i am running 6.2-STABLE. Kernel is 
>> GENERIC. I have my proc dev.cpu.0.freq=1000 to have temperature about 54 
>> Celsius. If a have dev.cpu.0.freq=1700, temperature is over 70 Celsius. Is 
>> this bug, unsuported acpi device or attribute my laptop?
>> My dmesg following:
> [-snip-]
>> Please, help me, all you will need (some sysctls or anything else) i
>> will send you.
> OK. People need to learn a bit about the normal temperatures of modern
> CPUs (as well as how they are measured).
> You have a 1.6GHz Pentium-M. The CPU temperature is measured on the
> silicon by a single junction that is tied to two pins on the
> package. The temperature you see is going to be higher than whet you saw
> on many older systems with a temperature sensor mounted under the CPU in
> the socket. These showed a lower temperature due to the combination of
> convection and thermal conduction.
> Your CPU is most likely a 735. If so, it is speced for operation to 100C
> and thermal shutdown forced at 125C. 70C is not really all that hot. My
> system tends to idle at about 55C and, during a big build
> (e.g. buildworld or will climb to about 85C. This is higher
> than I used to see, but I suspect I need to remove the keyboard and
> clean the heat sink. Dust accumulation can really impact thermal
> transfer and the laptop is now 2.5 years old.
> Really, what you are seeing is pretty normal. You can see what the
> vendor thought was too hot by looking at 'sysctl hw.sysctl.thermal'.
> Look at values for PSV and CRT. PSV is when the system should start
> aggressive thermal control by forcing the performance down. CRT is when
> the systems should alarm and, depending on configuration, start a
> shutdown.
> On my 2G Pentium-M I see:
> hw.acpi.thermal.tz0._PSV: 94.5C
> hw.acpi.thermal.tz0._CRT: 99.0C
> So even 80C is not excessive. Just very uncomfortable if you really have
> the laptop on your lap.

You should probably run powerd to drop the CPU to lower settings.  If
you're comparing to Windows XP, it uses an adaptive mode similar to
powerd when on or off AC power.  Most laptops are not designed any more
to run comfortably at 100%, they're designed to be comfortable with
adaptive cpu freq management but not self-destruct at 100%.


Also, see if you're using lower Cx levels for cpu idling.  They can make
a big heat difference.


man rc.conf


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