HowTo: Undervolt your notebook CPU for longer battery life

[pressureman]

Module for latest Intrepid kernel, 2.6.27-6-generic (32 bit)

[stillka]

Module for latest Intrepid kernel, 2.6.27-6-generic (32 bit)

thanks a much for providing compiled modules, it save time

[Black16V]

Hi,

where can I download the patch for 2.6.27 ?

[pressureman]

Module for latest Intrepid kernel, 2.6.27-7-generic (32 bit)

[pressureman]

where can I download the patch for 2.6.27 ?

The 2.6.26 patch works fine with 2.6.27.

http://phc.athousandnights.de/viewtopic.php?f=13&t=2

[virtuoso88]

Has anyone actually saved battery life? I read through all 22 pages and only 1 person mentioned something. I just did this on my W500 and my battery usage is exactly the same.

[linkmaster03]

This is not supposed to save battery life, it is supposed to make your PC cooler and quieter. Can ANYONE help me?

[Pogeymanz]

So, I followed this guide to undervolt, but my cpu is not running any cooler. What's up with that?

Here is lsmod | grep acpi_cpufreq:

acpi_cpufreq           14864  0 
freq_table              6400  1 acpi_cpufreq
processor              39744  2 acpi_cpufreq,thermal

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

10:2 8:2 6:2

Why wouldn't my CPU run any cooler? My defaults were:
10:40 8:35 6:29

[jmmL]

Pogeymanz, your output of " cat /sys/devices/system/cpu/cpu0/cpufreq/phc_controls " looks suspiciously low. If your CPU is anything like mine, the VIDs cannot be set any lower than the lowest factory VID - which is 19 in my case (with an Intel T5450) and looks to be 29 in your case.

You might want to try manually adjusting your VIDs to

10:29 8:29 6:29

Absolutely no guarantees that that won't harm your computer though; you have been warned.

Also, with regards to the battery life; it should help the CPU draw less power even when it's under load, and should therefore help extend battery life. Anecdotally, I'd say mine has improved by 5 minutes or so - compared to a vanilla install. Lowering my VIDs reduced the voltage across the cores by about 0.3V, which is about a 1/4 reduction in voltage. This should correspond to a 1/4 reduction in power drawn by the processor.

[Pogeymanz]

Thank you JimmL. Can I ask how you found your lowest factory VIDs? I forgot what the number is for my processor, but it's the Intel Dual Pentium 2.0 GHz.

So far my computer is stable. I even ran burnMMX just for funzies and nothing crashed or anything. I guess my temps under stress were a little lower than before, but idle temps are about the same. Maybe it did work and I was just expecting too much?