PowerNow! is effectively AMD’s version of Intel’s SpeedStep technology. The premise is a simple one: some applications require less processing power than others. Word processing, for example, consumes relatively few processor cycles, whereas playing a DVD, photo editing or running other media-rich applications requires more processor cycles to deliver a responsive level of performance.
AMD PowerNow! controls the level of processor performance automatically, dynamically adjusting the operating frequency and voltage many times per second, according to the task at hand. When an application does not require full performance, significant amounts of power can be saved. The Mobile Athlon 4 implementation of the technology allows for a total of 32 speed/voltage steps between 500MHz at 1.2V and the maximum clock speed of the processor. Realistically, in normal usage only between 4 and 8 steps are likely to be used. The only user-noticeable effect of PowerNow! technology is extended battery life.