Underclock your Android phone

SetCPU allows you to slow your phone's CPU to improve battery life.

Rooting your Android phone (or hacking it to give you root access) allows you to play in areas phone makers and telcos would rather you didn’t, and it allows you to take full control of your Android phone. You can perform tasks such as full backups and overclocking your phone’s CPU, which can provide added performance; for example, the 1GHz Qualcomm QSD8250 processor in the HTC Desire can be overclocked to 1.2GHz. You can also underclock your phone in order to improve battery life.

These days, there’s a decent argument that says smartphones come with more than enough horsepower and dual-core 1GHz chips will just lunch on your battery. Underclocking will reduce performance, but if you don’t need lightning speed, it can extend your run time.

SetCPU

SetCPU is available on the Android Market for US$1.99, but is also free to members of the XDA-Developers forum (http://forum.xda-developers.com). It allows you to use the cpufreq driver (similar to that found in Linux) and set the clock speed yourself. To ensure you don’t muck up your phone, you should use the ‘Autodetect Speeds Recommended’ option so that it offers you the correct clock settings for your phone’s CPU.

SetCPU needs root access and if you’re using the free XDA version, you’ll need an app installer (we recommend Gregory House AppInstaller) to get it on your phone. Make sure you read through the SetCPU splash screen information and know how to use it.

SetCPU allows you to set the maximum and minimum clock speed settings, as well as the methodology used to modulate clock rate. The Conservative setting is a good choice, as it takes a more gentle approach to the rate of increase, preserving battery life, and allows you to set clock speed rates based on current battery level using profiles, so you can drop it down when the battery is low.

Can I use SetCPU?

Because SetCPU works using Android’s cpufreq driver, the developer says it will work with “most if not all” rooted Android phones running at least Android 1.5. Get more information at http://www.setcpu.com.

Warning

Rooting your phone is a guaranteed way to void its warranty, so be warned and be careful. If anything goes wrong, you’re on your own. Also, SetCPU accesses low-level hardware, so be careful with it or you may find yourself with a bricked phone. It’s less likely you’ll damage your phone underclocking it than overclocking it. Using the auto-detected clock speeds is recommended.

Downclock your HTC Desire with SetCPU

1. Install SetCPU from the Android Market or join the XDA-Developers forum and download it. Launch it and read through the splash screen information. Click the ‘Autodetect Speeds Recommended’ button.

2. Allow SetCPU to have root access. Click the Remember box so you only have to go through this step once.

3. When the main screen appears, set the Scaling option to Conservative. Drag the maximum clock speed setting to the left and down to around 750MHz (you can go lower, but performance will be affected).

4. Tap the Info button to get more information about your phone, including the time spent at different clock settings.