I do not know how such a thing could be done. PSU's do not have anything built into them to do anything like that.
Overclocking should not increase CPU power consumption by more than 20% or so.
Case in point: My Q6600 at CPU VID (1.2625 volts) at stock speeds pulled about 8 amps as measured with a lab calibrated clamp-on ammeter. I separated the yellow wires from the black wires on the CPU power cable and clamped the ammeter around the yellow wires. At 3.6 GHz (vcore = 1.42 volts), the CPU pulled 9.5 amps.