Hardware Secrets posted Everything You Need to Know About the CPU C-States Power Saving Modes
In order to save energy when the CPU is idle, the CPU can be commanded to enter a low-power mode. Each CPU has several power modes and they are collectively called "C-states" or "C-modes". In this tutorial we will explain what these modes are, what they do and the modes supported by each processor.Everything You Need to Know About the CPU C-States Power Saving Modes