Mailing the story:
Reduce Linux power consumption
This three-part series is your starting point for tuning your system for power efficiency. In Part 1, get up to speed on the components and concepts you need to fine-tune a Linux-based System x server for power efficiency. Learn how to enable the Linux CPUfreq subsystem, get instruction on C and P states, and determine which of the five in-kernel governors you need to boost power efficiency on your system.