[kickopotomus]

We stopped chasing clock speeds because of the physical timing limitations of gate and signal propagation. Not because of heat. Suppose you are using a 5GHz clock. Every cycle is 0.2ns. Light can only travel 6cm in that time. Electricity propagates a little slower through a conductor (and even slower through silicon). So if you are using some insanely fast clock, you are just wasting cycles waiting for signals to move across the chip.

[yetihehe]

Current processors are no longer synchronous, each part now works asynchronously and there can be several instructions waiting to be completed at once, average Intructions Per Clock are already over 1, so there is no problem waiting a little more for signal to propagate.