SpeedStep – Wikipedia, the free encyclopedia

For example, for a 1.6 GHz Pentium M, the clock frequency can be stepped in 200 MHz increments over the range from 0.6 to 1.6 GHz. At the same time, the voltage requirement decreases from 1.484 V to 0.956 V. The result is that the power consumption theoretically goes down by a factor of 6.4.

via SpeedStep – Wikipedia, the free encyclopedia.