&gt; the cost in energy is directly proportionate to the clock frequency<p>Approximately true at lower frequencies, less accurate at higher frequencies.  Voltage must increase to reduce the transition times, at higher frequencies.  You can see this in any spec sheet.<p><a href="http:&#x2F;&#x2F;physics.stackexchange.com&#x2F;questions&#x2F;34766&#x2F;how-does-power-consumption-vary-with-the-processor-frequency-in-a-typical-comput" rel="nofollow">http:&#x2F;&#x2F;physics.stackexchange.com&#x2F;questions&#x2F;34766&#x2F;how-does-po...</a>