Intel® Pentium® Silver and Intel® Celeron® Processors Datasheet, Volume 1
Fully Integrated Voltage Regulator (FIVR)
The processor integrates multiple voltage rails in order to reduce BOM costs for the platform, and to enable additional voltage level features the processor can take advantage of.
There are FIVRs integrated on the PCH, VNN/V1P05 which is sourced from VCCIN_Aux. VCCIN_Aux also sourced the VCCSA rail in a CPU. In addition to VCCSA FIVR, compute die integrates 4 additional FIVRs to source VCCCORE, VCCSA, VCCL2, VCCGT and VCCRING, which derives the respective voltages from VCCIN VR on platform. Each FIVR is able to control a specific voltage rail.