Intel BX80646I54430, CM8064601466200, CM8064601466003 Adaptive Thermal Monitor, Frequency Control

Thermal Management—Processor

5.6Adaptive Thermal Monitor

The Adaptive Thermal Monitor feature provides an enhanced method for controlling the processor temperature when the processor silicon exceeds the Thermal Control Circuit (TCC) activation temperature. Adaptive Thermal Monitor uses TCC activation to reduce processor power using a combination of methods. The first method (Frequency control, similar to Thermal Monitor 2 (TM2) in previous generation processors) involves the processor reducing its operating frequency (using the core ratio multiplier) and internal core voltage. This combination of lower frequency and core voltage results in a reduction of the processor power consumption. The second method (clock modulation, known as Thermal Monitor 1 or TM1 in previous generation processors) reduces power consumption by modulating (starting and stopping) the internal processor core clocks. The processor intelligently selects the appropriate TCC method to use on a dynamic basis. BIOS is not required to select a specific method (as with previous-generation processors supporting TM1 or TM2). The temperature at which Adaptive Thermal Monitor activates the Thermal Control Circuit is factory calibrated and is not user configurable. Snooping and interrupt processing are performed in the normal manner while the TCC is active.

When the TCC activation temperature is reached, the processor will initiate TM2 in attempt to reduce its temperature. If TM2 is unable to reduce the processor temperature, TM1 will be also be activated. TM1 and TM2 will work together (clocks will be modulated at the lowest frequency ratio) to reduce power dissipation and temperature.

With a properly designed and characterized thermal solution, it is anticipated that the TCC will only be activated for very short periods of time when running the most power intensive applications. The processor performance impact due to these brief periods of TCC activation is expected to be so minor that it would be immeasurable. An under- designed thermal solution that is not able to prevent excessive activation of the TCC in the anticipated ambient environment may cause a noticeable performance loss, and in some cases may result in a TCASE that exceeds the specified maximum temperature and may affect the long-term reliability of the processor. In addition, a thermal solution that is significantly under designed may not be capable of cooling the processor even when the TCC is active continuously. See the appropriate processor Thermal Mechanical Design Guidelines for information on designing a compliant thermal solution.

The Thermal Monitor does not require any additional hardware, software drivers, or interrupt handling routines. The following sections provide more details on the different TCC mechanisms used by the processor.

Frequency Control

When the Digital Temperature Sensor (DTS) reaches a value of 0 (DTS temperatures reported using PECI may not equal zero when PROCHOT# is activated), the TCC will be activated and the PROCHOT# signal will be asserted if configured as bi-directional. This indicates the processor temperature has met or exceeded the factory calibrated trip temperature and it will take action to reduce the temperature.

Upon activation of the TCC, the processor will stop the core clocks, reduce the core ratio multiplier by 1 ratio and restart the clocks. All processor activity stops during this frequency transition that occurs within 2 us. Once the clocks have been restarted at the new lower frequency, processor activity resumes while the core voltage is reduced by the internal voltage regulator. Running the processor at the lower frequency and voltage will reduce power consumption and should allow the processor to cool off. If

Desktop 4th Generation Intel® Core™ Processor Family, Desktop Intel® Pentium® Processor Family, and Desktop Intel® Celeron® Processor Family

December 2013	Datasheet – Volume 1 of 2
Order No.: 328897-004	75