Enhanced SpeedStep is a series of dynamic frequency scaling technologies built
into some Intel microprocessors that allow the clock speed of the processor to be
dynamically changed (to different P-states) by software. This allows the processor
to meet the instantaneous performance needs of the operation being performed,
while minimizing power draw and heat generation. EIST was introduced in
several Prescott 6 series in the first quarter of 2005, namely the Pentium 4 660. ...
The power consumed by a CPU with a capacitance C, running at frequency f and
voltage V is approximately:.