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backwater

Member

From: Lima, Peru

Registered: 2019-09-17

Posts: 3  

Undervolting my CPU

Hello guys, I'm new to the forums

I was looking for ways to undervolt my trusty old T420 to have more battery life and better temperatures, I would like some guidance from more advanced users out there, perhaps some do's and dont's or a guide that has helped you guys in the past.

Thanks !

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Virtue et Silencio.

ToxicExMachina

Member

Registered: 2019-03-11

Posts: 210  

Re: Undervolting my CPU

Are you sure you need undervolting? AFAIK it's impossible without corresponding motherboard firmware. If you want to increase battery life you just need to set lower cpu frequency. The "cpupower" command will help. For example, the following commands will set cpu frequency to 1200MHz (i think it's minimal frequency for cpu installed in T420):

cpupower frequency-set -g performance
cpupower frequency-set -u 1200MHz

It works with intel_pstate power management.

Another important tweak for higher battery life is the backlight brightness. You can also buy external powerbank or additional batteries for your laptop.

backwater

Member

From: Lima, Peru

Registered: 2019-09-17

Posts: 3  

Re: Undervolting my CPU

Thanks for the info Toxic, I've been reading some documentantion on cpupower I'll test it out when im off work.
By the way, yesterday someone was kind enough to send an email to me with this app called TLP ( https://linrunner.de/en/tlp/docs/tlp-li … ement.html ) I successfully installed it on Devuan with the thinkpad extras and the GUI, seems like a very complete app if someone is interested. I will check if it is possible to have cpupower and TLP installed and running at the same time. perhaps this is not what I wanted in the beggining but you might be right about not being possible to undervolt my CPU. I'll either way continue my research and if I manage to do it i'll post it in the forums

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Virtue et Silencio.

ToxicExMachina

Member

Registered: 2019-03-11

Posts: 210  

Re: Undervolting my CPU

cpupower is just a simple tool for changing kernel power management settings. You can do the same and more with TLP.

As for CPU undervolting you can also check Coreboot. May be you will find some options for undervolting but i never heard about that on thinkpads.