I have a DELL E4300 laptop with backbox 5/ubuntu installed on it, i'm trying to change the value of the voltage corrsponding to the cpu frequencies. I've read that lowering them a bit don't change the cpu power but make a major difference in terms of temperatures and battery lifetime.

The CPU is a Intel(R) Core(TM)2 Duo CPU P9400 @ 2.40GHz My bios is the lastest version available for this laptop : A23, and there is no option to manage the voltage in it.

Here are the voltage i would like to set instead of the old ones :

0.925V @ 800MHz

0.975V @ 1600MHz

1.025V @ 2000MHz

1.037V @ 2400MHz

This can be done on windows by a software named CPUgenie...

I've read a lot and what is often proposed is to change the maximum and lower frenquencies of the cpu to save or gain power with cpufrequtils or others..

To be clear I want to keep my frequencies, but change the voltage corresponding to each of them.

Thank you in advance!


  • :::::::::::::::::::::::::::::::::::::::::::::: – pirogus Feb 26 '18 at 0:08

This is your classic XY problem where you ask how to change CPU voltage differently than how Intel does it when the frequency changes. In reality the question to ask is how to save battery life for more operational time.

This article addresses your issue in 8 simple steps:

  1. Set Ubuntu’s Built-In Power Settings
    • Open ‘System Settings’
    • Select the ‘Power’ icon
    • Adjust settings to suit your needs
  2. Turn off Bluetooth. Simple click the Bluetooth icon and:
    • Switch slider to ‘off’ (more recent versions of Ubuntu)
    • Click ‘turn off Bluetooth’ (older versions of Ubuntu)
  3. Turn off Wi-Fi
    • Click on the ‘Wi-Fi’ icon
    • Select the ‘Enable Wireless’ entry
  4. Lower Screen Brightness
    • Open System Settings
    • Select Brightness & Lock
    • Adjust the Brightness slider
  5. Unplug USB Drives, SD Cards, Discs, etc
    • Open a new File Manager window
    • Click the eject button on attached USB drives/SD cards
  6. Quit Apps You’re Not Using
  7. Avoid Adobe Flash (Where Possible)
    • Try to use a browser that configures Flash content to show ‘On Demand’. Firefox will prompt you to ‘enable’ Flash elements.
    • Google Chrome has a hidden ‘Plugin Power Saver’ option in chrome:flags that you can try.
  8. Install TLP. Options include:

    • Kernel laptop mode and dirty buffer timeouts
    • Processor frequency scaling including “turbo boost” / “turbo core”
    • Power aware process scheduler for multi-core/hyper-threading
    • Hard disk power management level and spin down timeout
    • Runtime power management for PCI(e) bus devices
    • Wi-fi power saving mode
    • Powering off disc drive
    • Audio power saving mode

Read the article for more details on each step.

| improve this answer | |
  • I'm not completely sure what powertop -c (calibrating) does, but I think it cut the power consumption of my laptop with 20%. – pa4080 Feb 25 '18 at 20:00
  • @pa4080 I only run off battery when ISP goes out and I'm forced to go to the library for Internet. About once every five years? Anyway I've heard many complain battery life in Linux is drastically less than Windows. So the 8 simple steps would interest most new users. I haven't used powertop myself but find tlp excellent for fan control and thermal management. – WinEunuuchs2Unix Feb 25 '18 at 20:03
  • i know about this solutions :) my answer still remain, I WANT to "change CPU voltage differently than how Intel does it when the frequency changes". I think thats an interresting thing to do, why use 1,15V to run at 2,4mhz when i can use 1.03V for the same performance. this is complementary to the 8 point you made! – pirogus Feb 26 '18 at 0:03
  • @pirogus Fair enough. I wouldn't be surprised though if changing the voltage is how they change the frequency. ie lower the voltage to lower the frequency and raising the voltage makes the frequency faster. But I can't say that is true. – WinEunuuchs2Unix Feb 26 '18 at 0:55
  • yes that is true, but what i want to do (and you can do it from windows so we can do it too) is to modify the volt values corresponding to the CPU speed, to change the "rules" so when the CPU gets 1.03V he says : "hey! lets go to 2.40Mhz". Cauz apparently he can reach it with a lower voltage! that's a thing you can usually do from the BIOS, but here I can't. – pirogus Feb 26 '18 at 1:40

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