STEEP-SLOPE DEVICES: FROM DARK TO DIM SILICON ALTHOUGH THE SUPERIOR SUBTHRESHOLD CHARACTERISTICS OF STEEP-SLOPE DEVICES CAN HELP POWER UP MORE CORES, RESEARCHERS STILL NEED CMOS TECHNOLOGY TO ACCELERATE SEQUENTIAL APPLICATIONS BECAUSE IT CAN REACH HIGHER

tion lets us pack more cores on the same die, thermal and power delivery constraints have precluded any scaling in the power bud-get available to these cores. This forces cores to operate at very low voltages (‘‘dim sili-con’’) to stay within the allotted power budg-ets. Unfortunately, low-voltage operation of silicon CMOS technology is extremely energy-inefficient. As the supply voltage approaches the threshold voltage, the transis-tor delay increases rapidly, resulting in a drop in the clock frequency. To avoid inefficient low-voltage operating points, CMOS multi-cores typically power on only a subset of the available cores and turn off the remainin