Scaling Intel Core 2 Duo

I was wondering if someone could explain the relatively limited CPU
frequency scaling points supported by the Core 2 Duo?

I have a P4 machine which can be scaled down to 375Mhz from 3 Ghz.

Yet the core 2 duo only supports 2.66Ghz or 2 Ghz. I'm assuming of
course that this is the CPU limit as opposed to it being a limit of the
Debian acpi_cpufreq module?

I dont know a lot about this stuff and do not overclock - since most of
time I am simply editing code, it seems to make sense to wind the CPU
down in most instances.

Richard Riley <> wrote:
> I was wondering if someone could explain the relatively limited CPU
> frequency scaling points supported by the Core 2 Duo?
>
> I have a P4 machine which can be scaled down to 375Mhz from 3 Ghz.

It's not really scalable that far; part of that's clock scaling, the rest is
internal throttling which is less efficient. If it's a desktop chip, it's
also incapable of changing the input voltage (although the notebook P4-M
chips did support dropping the voltage.)

> Yet the core 2 duo only supports 2.66Ghz or 2 Ghz. I'm assuming of
> course that this is the CPU limit as opposed to it being a limit of the
> Debian acpi_cpufreq module?

I'm not sure if the acpi_cpufreq module is now being recommended over the
enhanced speedstep module, but you could try switching to that one if the
Debian kernel has it (or if you compile your own kernel.)

In any case, the 2ghz speed may be the lowest your processor supports; in
general, it's a 6x multiplier, which would be 2ghz if you have one of the
newer Core 2 Duos (1333FSB, as opposed to the older 1066FSB ones which
should go down to 1.6ghz) Despite that, the processor should be able to
drop voltage and recognize idle time and keep quite cool and low power as
long as you have a decent governor running.

I've mostly just used the kernel-based "ondemand" governor, although you can
also use the "userspace" one plus one of the several CPU frequency daemons;
I'm not sure which one the debian guys like.

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