Thermal Specifications
When Intel Thermal Monitor 2 is enabled, and a high temperature situation is detected,
the Thermal Control Circuit (TCC) will be activated for all processor cores. The TCC
causes the processor to adjust its operating frequency (via the bus multiplier) and
input voltage (via the VID signals). This combination of reduced frequency and VID
results in a reduction to the processor power consumption. The lowest bus multiplier
for the Intel Thermal Monitor 2 is 8:1. This results in an operating frequency of
1066 MHz.
Once the new operating frequency is engaged, the processor will transition to the new
core operating voltage by issuing a new VID code to the voltage regulator. The voltage
regulator must support dynamic VID steps in order to support the Intel Thermal
Monitor 2. During the voltage change, it will be necessary to transition through multiple
VID codes to reach the target operating voltage. Each step will be one or two VID table
entries (see Table 2-2). The processor continues to execute instructions during the
voltage transition. Operation at the lower voltage reduces the power consumption of
the processor.
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 operating frequency and
voltage transition back to the normal system operating point. Transition of the VID code
will occur first, in order to ensure proper operation once the processor reaches its
normal operating frequency. Refer to Figure 6-5 for an illustration of this ordering.
Figure 6-5. Intel® Thermal Monitor 2 Frequency and Voltage Ordering
TTM2
Temperature
fMAX
fTM2
Frequency
VNOM
VTM2
Vcc
Time
T(hysterisis)
The PROCHOT_N signal is asserted when a high-temperature situation is detected,
regardless of whether Intel Thermal Monitor 1 or Intel Thermal Monitor 2 is enabled.
6.2.4
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 Intel Thermal Monitor 1 and Intel Thermal
Monitor 2 features. On-Demand mode is intended as a means to reduce system level
power consumption. Systems utilizing Intel Xeon Processor E7-8800/4800/2800
Product Families processor must not rely on software usage of this mechanism to limit
the processor temperature. There are two ways to implement On-Demand mode. If bit
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