Platform Environment Control Interface (PECI) is an Intel proprietary single wire serial interface that provides a communication channel between Intel processors and chipset components to external system management logic and thermal monitoring devices.
PECI was introduced in 2006 with the Intel Core 2 Duo microprocessors.
These sensors, after being calibrated at the factory, are able to provide digital data concerning processor temperature information.
From a control standpoint, the main difference between PECI and the previously used thermal monitoring methods is that PECI reports a negative value expressing the difference between the current temperature and the thermal throttle point (at which the CPU reduces speed or shuts down to prevent damage due to overheating) instead of the absolute temperature.
Since the value reported by PECI takes into account internal processor information about safe operating temperatures, it alleviates the need for the BIOS or operating system to make potentially incorrect assumptions about this limit.