Modern synchronous techniques can already be low overhead, take a look at "slew tolerant" circuits where you can have not flip-flop setup/hold delays in the cir

Modern synchronous techniques can already be low overhead, take a look at "slew tolerant" circuits where you can have not flip-flop setup/hold delays in the circuit path: http://pages.hmc.edu/harris/class/e158/01/lect21.pdf http://pages.hmc.edu/harris/class/e158/01/lect21.pdf Also, big CPUs are power limited anyway. I mean "speed step" allows one core to run fast, as long as the others are unloaded.