Modern x86 chips have built in support for voltage drops, as part of margin recovery. As the chip changes activity profile increasing current draw (e.g. turning

Modern x86 chips have built in support for voltage drops, as part of margin recovery. As the chip changes activity profile increasing current draw (e.g. turning on all cores for multithreaded code) the voltage will drop until the regulators catch up. "Back in the day" you used margin to accommodate this. Today, circuitry detects these events on the fly and slows down the chip for a few microseconds waiting for the voltage to recover. This allows you to remove margin and operate closer to the limit.