HowTo: Undervolt your notebook CPU for longer battery life

[eldragon]

2.6.27-generic kernel acpi_cpufreq file (another compiled version):

Try this attached acpi_cpufreq file for all those who have the upgraded 2.6.27-generic kernel installed. I'm afraid the one that's originally posted does not work for most people.

Anyways, thanks for the help. I went from an idle 24 watts with 2 hours of battery life to 12.8 watts with 4 hours of battery life!

dont you mean 2.6.24.17?

im trying right now with this file and the newer kernel, but i dont think there will be any difference....

how did you measure power consumption?

[krlhc8]

woops, sorry: 2.6.24-17-generic (twas a long night!). I used Intel's powertop application to find the power consumption. Did the file work for you?

[krlhc8]

acpi-cpufreq.ko: ELF 64-bit LSB relocatable, x86-64, version 1 (SYSV), not stripped

It probably mainly works for those people running 64 bit kernels

Good point

[eldragon]

woops, sorry: 2.6.24-17-generic (twas a long night!). I used Intel's powertop application to find the power consumption. Did the file work for you?

it did work, but it running the script goes all the way to zero. and leaves me (after tweaking the results a bit to let it finnish) with something like:
2 1 1 1 1 1 1 1 for all freqs. (computer never freezes).

i guess my notebook isnt giving a rat's *** about what undervoltage i give to it.

anyone experiencing this? know of a fix for it? i really long for the above 1hour battery life too

[stred]

2.6.24-17-generic kernel acpi_cpufreq file (32-bit x86 processor compiled version):

Try this attached acpi_cpufreq file for all those who have the upgraded 2.6.27-generic kernel installed. I'm afraid the one that's originally posted does not work for most people.

Anyways, thanks for the help. I went from an idle 24 watts with 2 hours of battery life to 12.8 watts with 4 hours of battery life! (I used Intel's powertop application fyi)

thnks for the module, it worked..instant magic

[Sebastral]

This is so awesome!! I fixed up a gutsy 2.6.22-14-generic kernel by following this other guide, and for finding the voltages I used the optimizer script. It gave me the shits, cause after every lock up I got an 'error 16 - inconsistent file system' and I had to run reiserfsck --check to fix it, but I got the results;

Default VIDs: 15 14 13 11 10 7
Current VIDs: 7 5 3 1 1 1

I actually changed it to 7 5 3 1 0 0 initially but then I realized I didn't really know what I was doing. But because the script adds 2 to the lowest VID tested I'm wondering if a VID of -1 is possible? and what about 0? The other guide says 'remember: you can not set lower VIDs than the lowest default VID'. is that true?

I haven't done a full battery unload yet btw, but the remaining time remains stable while remaining percentage goes down.. I guess it needs calibration..

edit; mm, just got a lockup doing nothing special so I now put in 12:7 11:6 10:5 9:4 8:3 6:1 which makes more sense anyway

[pambos]

Hey guys...
Running the script goes all the way to zero, then tries -1 and the PC crashes. It gave me a message "Recovering CPU", and I waited for a couple of minutes, but it did not recover. Is there anything wrong ? Shouldn't it have stopped before 0 ?

Thanks in advance!

[pambos]

Bump

[eldragon]

Bump

ive got the same problem, but computer never froze.

my take is acpi_freq isnt working as advertised with some hardware configurations. (it isnt undervolting at all).

[skinnie]

Hi,first of all thanks for this how to.In windows I have undervolted my T7300 to 0.937v@2.0GHz,and had that undervolt in my last 7.10 installation.
Now I am running a fresh install of kubuntu 64bit,and when I make the

cat /sys/devices/system/cpu/cpu0/cpufreq/phc_controls

it says file or folder inexistant (translation of portuguese).
Any thoughts?
Undervolt again would be perfect