Intel 5148LV - Xeon Dual Core Active H Datasheet page 83

Thermal Specifications
When the Thermal Monitor 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 Thermal Profile A, 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. A
thermal solution that is designed to Thermal Profile B may cause a noticeable
performance loss due to increased TCC activation. Thermal Solutions that exceed
Thermal Profile B will exceed the maximum temperature specification and 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. Refer to the Dual-Core Intel
Thermal/Mechanical Design Guidelines or information on designing a thermal solution.
For the Dual-Core Intel® Xeon® Processor LV 5138, 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. Utilization of
a thermal solution that exceeds the Short-Term Thermal Profile, or which operates at
the Short-Term Thermal Profile for a duration longer than the specified limits, do not
meet the processor's thermal specifications and may result in permanent damage to
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. Refer
to the Dual-Core Intel® Xeon® Processor LV 5138 in Embedded Applications Thermal/
Mechanical Design Guideline for information on designing a thermal solution." The duty
cycle for the TCC, when activated by the Thermal Monitor, is factory configured and
cannot be modified. The Thermal Monitor does not require any additional hardware,
software drivers, or interrupt handling routines. Refer to the Dual-Core Intel® Xeon®
Processor LV 5138 in Embedded Applications Thermal/Mechanical Design Guideline for
information on designing a thermal solution.
6.2.1.2 Enhanced Thermal Monitor (TM2)
The Dual-Core Intel
Thermal Monitor capability known as Thermal Monitor 2 (TM2). This mechanism
provides an efficient means for limiting the processor temperature by reducing the
power consumption within the processor. TM2 requires support for dynamic VID
transitions in the platform.
When TM2 is enabled, and a high temperature situation is detected, the Thermal
Control Circuit (TCC) will be activated for both 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.
A processor enabled for TM2 includes two operating points, each consisting of a specific
operating frequency and voltage, which is identical for both processor cores. The first
operating point represents the normal operating condition for the processor. Under this
condition, the core-frequency-to-system-bus multiplier utilized by the processor is that
contained in the CLOCK_FLEX_MAX MSR and the VID that is specified in
® ®
Dual-Core Intel Xeon Processor 5100 Series Datasheet
® ®
Xeon Processor 5100 Series adds supports for an Enhanced
® ®
Xeon Processor 5100 Series
Table 2-3.
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