In an open-loop system, a voltage regulator supplies a fixed voltage to a core of an ASIC or SoC. In a close-loop AVS system, a Hardware Performance Monitor, or HPM, is embedded in the ASIC to monitor the process and temperature variation of the core. This information is communicated to the Advanced Power Controller (APC) to determine if there is a voltage optimization that can be done. The voltage optimization is then communicated to the Energy Management Unit (EMU) through the PWI interface. The EMU then closes the loop by supplying the most optimized voltage back to the core of the ASIC.