Proof of concept code for efi boot loader which undervolts or overclocks a CPU before starting the OS.

Current status: Underclocking/Undervolting has been tested on an A10-5700 and works. Changing settings requires recompilation.

Compilation: The code has been developed on an Arch Linux 64 bit system. Install gnu-efi-libs and type make to compile.

Installation: Copy the undervolt.efi file to the EFI system partition and add a boot entry from the UEFI firmware or using efibootmgr/EasyUEFI.

Known issues:

• The code does not support multipliers below 16. I don't change idle P-states, so I haven't bothered adding support. Please search for CoreCOF in the BIOS and Kernel Developer Guide if you want to add support.
• Only 15h (Trinity) APUs are supported. Check AmdMsrTweaker or the relevant BKDG for required changes for other families.