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Re: Software CPU cooling - apm / acpi

On Thu, Dec 05, 2002 at 08:18:40PM +0100, Olivier Guyotot wrote:
> hi,
> I would like to cool my CPU in the same way CPUIdle does it under
> windows : using the Hlt instruction when the CPU is idle. 

Linux does this by default.  Please don't assume that Linux repeats
the same broken mistakes Windows does, as this is almost never the

>  *         Daemonize now gets rid of our controlling terminal (sfr).
>  *         CONFIG_APM_CPU_IDLE now just affects the default value of
>  *         idle_threshold (sfr).
>  *         Change name of kernel apm daemon (as it no longer idles) (sfr).
> So it seems that apm no longer idles: how can I do it then?

That's laptop specific; while desktop systems can do this, too, the
power savings and heat dissapation is epsilon on desktops compared to
what linux already does.

Just to clarify: HLT is a CPU feature standard on i386 architecture,
not an APM or ACPI feature.

> My CPU is more than 20°C over the motherboard's temperature when I run
> linux (that is 60°C, sometimes 65°), while it's only 3/4°C under windows
> and a software cooler (dropping to 35/40°C)! And I can't afford to
> change my CPU Cooler just now...

This would presumably be due to Linux not using the BIOS unless it
can't possibly do something on it's own, wheras Windows depends on the
BIOS for every little tiny detail.  Hence the need for drivers for
large hard drives on older systems under Windows, but not under Linux,
among other details.  

About the only way you can narrow that gap down a bit under Linux is
to start investing in water cooling, though this is serious overkill
unless you're overclocking.  I used to have 30C differences between
the system and CPU temps before I got into overclocking, though both
temps were still well inside spec.  I got a Koolance case and
overclocked the CPU by about 25%.  The water cooling is still overkill
when overclocking this little, my CPU is only about 4C warmer than the
system temp while mostly idle.

For those interested, I pull around 225 frames per second, never lower
than 30 and never greater than 325 in UT, depending on system load.

 .''`.     Baloo <baloo@ursine.dyndns.org>
: :'  :    proud Debian admin and user
`. `'`
  `-  Debian - when you have better things to do than to fix a system

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