12th Generation Intel® Core™ Processors Datasheet, Volume 1 of 2
Digital Thermal Sensor
Each processor has multiple on-die Digital Thermal Sensor (DTS) that detects the processor IA, GT and other areas of interest instantaneous temperature.
When the temperature is retrieved by the processor MSR, it is the instantaneous temperature of the given DTS. When the temperature is retrieved using PECI, it is the average of the highest DTS temperature in the package over a 256 ms time window. Intel recommends using the PECI reported temperature for platform thermal control that benefits from averaging, such as fan speed control. The average DTS temperature may not be a good indicator of package Adaptive Thermal Monitor activation or rapid increases in temperature that triggers the Out of Specification status bit within the PACKAGE_THERM_STATUS (0x1B1) MSR and IA32_THERM_STATUS (0x19C) MSR.
Code execution is halted in C1 or deeper C-states. Package temperature can still be monitored through PECI in lower C-states.
Unlike traditional thermal devices, the DTS outputs a temperature relative to the maximum supported operating temperature of the processor (TjMAX), regardless of TCC activation offset. It is the responsibility of software to convert the relative temperature to an absolute temperature. The absolute reference temperature is readable in the TEMPERATURE_TARGET (0x1A2) MSR. The temperature returned by the DTS is an implied negative integer indicating the relative offset from TjMAX. The DTS does not report temperatures greater than TjMAX. The DTS-relative temperature readout directly impacts the Adaptive Thermal Monitor trigger point. When a package DTS indicates that it has reached the TCC activation (a reading of 0x0, except when the TCC activation offset is changed), the TCC will activate and indicate an Adaptive Thermal Monitor event. A TCC activation will lower both processor IA core and graphics core frequency, voltage, or both. Changes to the temperature can be detected using two programmable thresholds located in the processor thermal MSRs. These thresholds have the capability of generating interrupts using the processor IA core's local APIC. Refer to the Intel 64 Architectures Software Developer’s Manual for specific register and programming details.
Digital Thermal Sensor Accuracy (T_accuracy)
The error associated with DTS measurements will not exceed ±5 °C within the entire operating range.
Fan Speed Control with Digital Thermal Sensor
Digital Thermal Sensor based fan speed control (TFAN) is a recommended feature to achieve optimal thermal performance. At the TFAN temperature, Intel recommends full cooling capability before the DTS reading reaches TjMAX.