[ianhowson]

Under some constraints [1] [2] if you halve the frequency and double the number of execution units, the overall power consumption drops.

Therefore, you could gain performance or reduce power by stacking layers of silicon.

This is also true for things like power LEDs; within a certain range of their operating curve (current vs. output) you can reduce current by X% and lose less than X% of output. Put down two LEDs, then, and you get more output at the same current.

[1] architectures that scale efficiently to more execution units, like GPUs

[2] you're in a suitable region of the frequency-power curve

[phkahler]

Yes, the last 10 percent increase in clock speed causes a 30 percent increase in power, or something like that. If you care about total performance instead of single thread it's probably better to add more cores.