Thermal Specifications
6.2
Processor Thermal Features
6.2.1
Thermal Monitor Features
The Intel Xeon Processor E7-8800/4800/2800 Product Families processor provides two
thermal monitor features, Intel Thermal Monitor 1 (“TM1”) and Intel Thermal Monitor 2
(“TM2”). Both Intel Thermal Monitor 1 and 2 must be enabled in BIOS for the processor
to be operating within specifications. When both are enabled, Intel Thermal Monitor 2
will be activated first and Intel Thermal Monitor 1 will be added if Intel Thermal Monitor
2 is not effective.
®
6.2.2
Intel Thermal Monitor 1
The Intel Thermal Monitor 1 feature helps control the processor temperature by
activating the Thermal Control Circuit (TCC) when the processor silicon reaches its
maximum operating temperature. The TCC reduces processor power consumption as
needed by modulating (starting and stopping) the internal processor core clocks. Intel
Thermal Monitor 1 or Intel Thermal Monitor 2 must be enabled for the processor to be
operating within specifications. The temperature at which Intel Thermal Monitor 1
activates the thermal control circuit is not user-configurable and is not software-visible.
Bus traffic is snooped in the normal manner, and interrupt requests are latched (and
serviced during the time that the clocks are on) while the TCC is active.
When Intel Thermal Monitor 1 is enabled, and a high temperature situation exists (that
is, TCC is active), the clocks will be modulated by alternately turning the clocks off and
on at a duty cycle specific to the processor (typically 30 - 50%). Cycle times are
processor speed dependent and will decrease as processor core frequencies increase. A
small amount of hysteresis has been included to prevent rapid active/inactive
transitions of the TCC when the processor temperature is near its maximum operating
temperature. Once the temperature has dropped below the maximum operating
temperature, and the hysteresis timer has expired, the TCC goes inactive and clock
modulation ceases.
With a thermal solution designed to meet the Intel Xeon Processor E7-8800/4800/2800
Product Families processor Thermal Profiles, it is anticipated that the TCC would 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. 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.
The duty cycle for the TCC, when activated by the Intel Thermal Monitor 1, is factory-
configured and cannot be modified. Intel Thermal Monitor 1 does not require any
additional hardware, software drivers, or interrupt handling routines.
6.2.3
Intel Thermal Monitor 2
The Intel Xeon Processor E7-8800/4800/2800 Product Families processor adds
supports for an enhanced thermal monitor capability known as Intel Thermal Monitor 2.
This mechanism provides an efficient means for limiting the processor temperature by
reducing the power consumption within the processor. Intel Thermal Monitor 1 or Intel
Thermal Monitor 2 must be enabled for the processor to be operating within
specifications. Intel Thermal Monitor 2 requires support for dynamic VID transitions in
the platform.
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