This article describes the Bios and Windows XP settings needed to activate the Cool n' Quiet feature on AMD chips.
IMPORTANT NOTE!: If you are having overheating issues, Cool n' Quiet will not solve the problem. Please refer to this article if you are experiencing lockups or emergency shutdowns, or this article if your computer won't even boot.
Step 1: Get the latest CnQ drivers from the AMD website.
If you are using a Phenom chip, the software is here: www.amd.com/us-en/assets/content_type/utilities/AMD_Processor_Driver_1320053.zip
If you are not using a Phenom, the correct driver can be located here:
www.amd.com/us-en/Processors/TechnicalResources/0,,30_182,00.html
Step 2: Enable software control of voltage in BIOS
After you have installed the latest processor drivers from AMD get into BIOS and allow software to make changes to hardware.
First, reboot, and get into BIOS by pressing "delete" after the screen that shows your graphics card information.