Granola, formerly known as MicroMiser, is a energy saving software for Windows and Linux computer systems that uses algorithms to find the ideal balance between energy saving and performance requirements.

The cross-platform application Granola offers an unobtrusive method of saving energy. It concentrates its energy saving efforts on the cpu by using dynamic voltage and frequency scaling technologies. It basically means that the cpu will be lowered or raised depending on the power requirements of the system.
Link (I took the quote from here)

Note your motherboard must support DVFS for the app to work. Mine didn't, but I thought I could share this here anyway.