How to undervolt Samsung Galaxy S2?

Overclock and overvolt terms are very common on computer PC. However, this will increase power usage and generate more heat. Not so good to try it on smartphone. So the other ways ~ underclock and undervolt should be better on smartphone like Samsung Galaxy S II, right? Yes, to improve battery life. Underclock may not be so efficient in performance / walt ratio. But undervolt surely will improve battery life while maintain the overall performance speed.

Undervolt Samsung Galaxy S2

For example, by underclock from 1.2 GHz to 1 GHz, speed performance drops 16.67% but voltage usage drops 6% only from 1250 mV to 1175 mV. Therefore, it is better to just undervolt only and keep the highest speed stage. Let’s say by reducing voltage from 1250 mV to 1150 mV at 1.2 GHz speed stage, you will get 8% voltage usage reduction while maintaining 1.2 GHz speed.

How to undervolt Samsung Galaxy S2?

  1. Install custom kernel that support undervolt.
  2. Install SetCPU.
  3. At Voltages tab, select the desire value for each speed stages.
  4. Note – try to reduce 25 mV each time.
  5. Click Apply then.
  6. Run Stress test ~ Stress CPU to test stability (located at Info tab).
  7. That’s all.

Note – Only check ‘Set on Boot’ when you are confident that the undervolted values won’t hang and stable all the time.

Each phone has its own CPU chipset. Other people’s SetCPU voltages settings may not work for you. Therefore, you need to try lot of the settings until you get the lowest voltages and stable for daily use.


  1. okay – i just installed setCPU 2.2.4 on my SGSII and unfortunately, there is no Voltages tab when i run it.
    I’d like to undervolt my unit. pls help

  2. Do you have a link to a kernel that supports under clocking?

    Just got the skyrocket and the battery life is pretty awful. I’m using the stock rom now, but I’ll probably be swapping to something else shortly.

  3. Thanks…now if iam uninstalling setcpu…it will take the deafault
    Samsung’s settings right? I want to get rid of it and keep my factery
    Settings samsung provided…..please advice…..
    Becoz after installing goes tosleep sometime…thats the problem for me.

  4. Thanks Jayce. I have done below steps and It worked.

    1) Set clock speed 1200 Mhz max and 200 Mhz min.
    2) check ‘Set on Boot’
    3) Reboot the phone
    4)Verify settings again by going to ‘Main’ tab.
    5) From Application, clear data and uninstall.

    Now I don’t have crashing issue.

    Thanks ..


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