[sclug] Under(re)volting - How does MS do it?

ed ed at s5h.net
Thu Mar 1 19:44:24 UTC 2007

On Wed, 28 Feb 2007 22:52:45 +0100
Pieter Claassen <pieter at claassen.co.uk> wrote:

> Hi Guys, I just got a brand new lenovo X60s from the Uni (which I am
> now regretting because it works so badly with Linux).
> Many things don't work (most notably switching between external VGA
> and the laptop screen, increasing screen brightness, disabling
> wireless and bluetooth etc.).
> But, what is really worrying is that the battery barely lasts 2 hours
> on this thing, even with dual cores (Intel Dual Core 1.66GHz with
> 2400MB Cache). The cpufreq governor works fine for both cpu's but
> only has three steps (1,1.33 and 1.66 GHz).
> So, the question is simply: How come Microsoft manages to get around 6
> hours out of this battery (urban legend) while the best I can do
> (after manually disabling wireless, unloading USB drivers, enabling
> laptop mode) is only 2 hours? Yes, I know P=V^2/R which I suspect
> that even a minor drop in board voltage will have significant power
> gains. However, everything I read warns me against patching the
> kernel for undervolting because of possible hardware damage
> (motherboard not chip).
> So, how is Microsoft doing this? How can I do this?

idle cycles on the cpu i imagine.

make sure one has cpu idle enabled in APM.

if you have ubuntu i think that's already enabled, but make sure you
have apm loaded at startup.


there are things like cpu scaling so the cpu cycles at a lower speed
when the battery is running low, or in little use. i don't know so much
about that as i tend not to need it, but i guess if everyone used this
they'd save a bit on the electricity bill per year.

The dirt trail to the moon pop is breakdancing because of the power of
the dark side. Qwest is blasting through 30 million dollars

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