VCC Voltage Identification (VID)

Intel processors/chipsets are individually calibrated in the factory to operate on a specific voltage/frequency and operating-condition curve specified for that individual processor. In normal operation, the processor autonomously issues voltage control requests according to this calibrated curve using the serial voltage-identifier (SVID) interface. Altering the voltage applied at the processor/chipset causing operation outside of this calibrated curve is considered out-of-specification operation.

The SVID bus consists of three open-drain signals: clock, data, and alert# to both set voltage-levels and gather telemetry data from the voltage regulators. Voltages are controlled per an 8-bit integer value, called a VID, that maps to an analog voltage level. An offset field also exists that allows altering the VID table. Alert can be used to inform the processor that a voltage-change request has been completed or to interrupt the processor with a fault notification.