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Thermal Management Specifications
112 Intel® Xeon® Processor E5-1600 v2/E5-2600 v2 Product Families
Datasheet Volume One of Two
SVID/frequency points. Transition of the SVID code will occur first, to insure proper
operation once the processor reaches its normal operating frequency. Refer to
Figure 5-6 for an illustration of this ordering.
5.2.2.2 Clock Modulation
Clock modulation is performed by alternately turning the clocks off and on at a duty
cycle specific to the processor (factory configured to 37.5% on and 62.5% off for TM1).
The period of the duty cycle is configured to 32 microseconds when the TCC is active.
Cycle times are independent of processor frequency. 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. Clock
modulation is automatically engaged as part of the TCC activation when the
Frequency/SVID targets are at their minimum settings. It may also be initiated by
software at a configurable duty cycle.
5.2.3 On-Demand Mode
The processor provides an auxiliary mechanism that allows system software to force
the processor to reduce its power consumption. This mechanism is referred to as “On-
Demand” mode and is distinct from the Adaptive Thermal Monitor feature. On-Demand
mode is intended as a means to reduce system level power consumption. Systems
must not rely on software usage of this mechanism to limit the processor temperature.
If bit 4 of the IA32_CLOCK_MODULATION MSR is set to a ‘1’, the processor will
immediately reduce its power consumption via modulation (starting and stopping) of
the internal core clock, independent of the processor temperature. When using On-
Figure 5-6. Frequency and Voltage Ordering