HowTo: Undervolt your notebook CPU for longer battery life

[HellBoyz77]

I followed the guide with just some changes for match my machine.

I have a T5500 Core 2 Duo, Hardy x86.

The script linux-phc-optimize.bash did not work for me, it gave the -1 issue. Also running the script with another istance of burnMMX in a separate tab made the temperature up to 104 degree, it's almost the limit that can support. So, be aware on using it.

Instead i suggest if you have this type of cpu to put the VID at 19, as other users say seems that is impossibile to set a lower level.

You can use PHCTools to set the VID for both the cpu, just pay attention to mark the option "Restore VIDs on Load" under Settings Tab. Before using it launch the script install.sh to set the permissions.

I can confirm that the average temperature has dropped around 10-15 degree.

The compiled module for 2.6.24-19 32bit is below.

Good job Ares Drake.

[mailforbiz]

I have Intel 7250 C2D, x86. I followed the steps in the original post and used the PHC patch for kernel -16. The original values I got on doing a cat of phc_controls were

$ cat /sys/devices/system/cpu/cpu0/cpufreq/phc_controls
11:45 10:37 8:30 6:23 136:15

That doesn't seem right, esp the last pair 136:15. From what I understand, the first value should be much lower.

Can anyone with knowledge of this confirm whether this values sound fishy ?

By the way, I still went through the rest of the steps and the script gives me the -1 issue.

Maybe I need to compile my own patch.

Any response appreciated.

TIA,
HT

[SyntheticShield]

does this how to work with AMD processors, or does this only work with dual core processors?

[mailforbiz]

I went ahead and put 19 as the voltage values for all the frequencies like some folks here have done. I would say there has been maybe a 3-4 deg drop in the temp but not the 10-15 deg some folks have reported. But this could just be my perception. I haven't tried compiling the patch myself yet. Don't know if this matters but I'm using kernel -16.

I have Intel 7250 C2D, x86. I followed the steps in the original post and used the PHC patch for kernel -16. The original values I got on doing a cat of phc_controls were


That doesn't seem right, esp the last pair 136:15. From what I understand, the first value should be much lower.

Can anyone with knowledge of this confirm whether this values sound fishy ?

By the way, I still went through the rest of the steps and the script gives me the -1 issue.

Maybe I need to compile my own patch.

Any response appreciated.

TIA,
HT

[blazercist]

I'd like to try this but before I do can someone confirm this actually has a positive effect on battery life? Can someone post some detailed values in reference to "before and after" battery life. Thanks

[aashay]

Ill gladly run the tests given the right tools. Right now, I can say there has been a marginal increase (10-20 mins). Though the 10-15 degs reduction in temperature makes the whole thing worth it

[mailforbiz]

I don't know how you guys are getting a 10-15 degrees drop. I played around quite a bit to come up with VID values that didn't freeze my laptop. Eventually though, setting the VIDs at those values made my HDD temp go upto 46 deg when earlier it used to hover around 42 deg. Besides it didn't make much difference for my other temps - GPU and cores. So for now I've reverted back to the original values. Maybe I'm doing something wrong.

Has anyone measured the before/after HDD temp using hddtemp ?

I'd love to get the 10-15 deg drop as my laptop gets quite hot and this is one annoying thing which makes me pine for Vista. Oh Gosh, nooooooooooooo!! [Realizes with horror what he just said]

[aashay]

hddtemp shows equal if not lower values after the undervolt.

[jocko]

Has anyone measured the before/after HDD temp using hddtemp ?

Why do you think undervolting the cpu would change the hdd temperature?
It will only change the cpu temperature, nothing else.

[mailforbiz]

Good question, I have no idea why the HDD temp would rise. I was running burnMMX at times but that is only supposed to exert the cpu so who knows. In short, either the steps depicted in this tutorial don't work for my cpu/system configuration else I'm being a braindead bugger and doing something wrong. Either way, there are unpleasant side-effects.

Why do you think undervolting the cpu would change the hdd temperature?
It will only change the cpu temperature, nothing else.