Thermal Management—Processor

Error and Thermal Protection Signals on page 83). THERMTRIP# activation is independent of processor activity. The temperature at which THERMTRIP# asserts is not user configurable and is not software visible.

5.8Digital Thermal Sensor

Each processor execution core has an on-die Digital Thermal Sensor (DTS) that detects the core's instantaneous temperature. The DTS is the preferred method of monitoring processor die temperature because:

•It is located near the hottest portions of the die.

•It can accurately track the die temperature and ensure that the Adaptive Thermal Monitor is not excessively activated.

Temperature values from the DTS can be retrieved through:

•A software interface using processor Model Specific Register (MSR).

•A processor hardware interface as described in Platform Environmental Control Interface (PECI) on page 36.

When temperature is retrieved by the processor MSR, it is the instantaneous temperature of the given core. When 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 MSR 1B1h and IA32_THERM_STATUS MSR 19Ch.

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 MSR 1A2h. 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 0h, 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 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 core's local APIC. Refer to the Intel® 64 and IA-32 Architectures Software Developer’s Manual for specific register and programming details.

5.8.1Digital Thermal Sensor Accuracy (Taccuracy)

The error associated with DTS measurements will not exceed ±5 °C within the entire operating range.

 

Intel® Xeon® Processor E3-1200 v3 Product Family

June 2013

Datasheet – Volume 1 of 2

Order No.: 328907-001

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