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Lower your CPU voltage to reduce heat and fan noise
09 September, 2006 in CPU
This is a tip for Intel® CPU owners who consider themselves to be advanced users. This isn't tested, it may not work for you, and it's not something we support. However, if you want to reduce the fan noise and heat output of your laptop, this might help. It should work with Intel® Pentium® M CPUs that have the SpeedStep feature (Core™ Duo support is just starting to be found in some software). I've been reducing my Intel® Pentium® M voltage and controling the clock speed for over a year. It usually provides an extra 5-10 minutes of battery life, and the laptop doesn't feel as hot or loud. Notebook Hardware Control (NHC) is the first piece of software to try. More are linked at the bottom.
Another warning: When you set the voltage too low, your computer will crash. Before testing new voltages, close all running programs and reboot. That way you won't lose any data when your system crashes. Also, don't save the voltage to start up automatically or you may not get the computer working again until going into safe mode or reinstalling Windows Also, be aware the voltage and clock multiplier may reset after plugging or unplugging the laptop.
One final warning: If you are having support issues with your laptop, please make sure your CPU is running at all the defaults. Very frequently, unofficial drivers or mods are the cause of support problems.
The default voltage for most lower clock speed Intel® Pentium® Ms is 1.356v. I've found mine is rock solid at 1.068v at 1.6 GHz, and it crashes at .anything lower than 1.03v at that speed. When I go on battery and really want to conserve battery life, I switch to a 6x multiplier (600-800 MHz) at .988v. The .988v voltage will crash the system at 1.6 GHz but run fine at 600-800 MHz so be careful to increase the voltage if increasing the clock speed.
Intel® Pentium® M CPUs with higher clock speeds will likely require higher voltages to be stable. Different laptops have different cooling systems. It will require experimentation to get right. It's easiest to use NHC to test stability since it runs a test automatically when changing voltage. I recommend bumping the voltage up a couple notches once you've found a voltage that isn't stable. It's better to keep a little margin rather than have none at all.
Notebook Hardware Control (NHC), CrystalCPUID, and RMClock are the top 3 undervolting applications. Sometimes, one application won't work with a certain laptop, so if you have problems, try all three. Uninstall the ones you don't use.
More Links:
http://www.overclockers.com/tips1206/
http://www.nordichardware.com/Articles/?page=1&skrivelse=465