Intel E5205 - Cpu Xeon 1.86Ghz Fsb1066Mhz 6M Lga771 Dual Core Tray Datasheet page 86

When the 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 thermal solutions designed to the Dual-Core Intel® Xeon® Processor E5200
Series, Dual-Core Intel® Xeon® Processor L5200 Series and Dual-Core Intel® Xeon®
Processor X5200 Series Thermal Profile, 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. Refer to the Dual-
Core Intel® Xeon® Processor 5200 Series Thermal/Mechanical Design Guidelines
(TMDG) for information on designing a thermal solution.
The duty cycle for the TCC, when activated by the Intel® Thermal Monitor 1, is factory
configured and cannot be modified. The Intel® Thermal Monitor 1 does not require any
additional hardware, software drivers, or interrupt handling routines.
6.2.1.2 Intel® Thermal Monitor 2
The Dual-Core Intel® Xeon® Processor 5200 Series 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 2 requires support for
dynamic VID transitions in the platform.
Note: Not all Dual-Core Intel® Xeon® Processor 5200 Series are capable of supporting
Intel® Thermal Monitor 2. More detail on which processor frequencies will support
Intel® Thermal Monitor 2 will be provided in future releases of the Dual-Core Intel®
Xeon® Processor 5200 Series Thermal/Mechanical Design Guidelines (TMDG) when
available. For more details also refer to the Intel® 64 and IA-32 Architectures Software
Developer's Manual.
When Intel® Thermal Monitor 2 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 Intel® Thermal Monitor 2 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
The second operating point consists of both a lower operating frequency and voltage.
The lowest operating frequency is determined by the lowest supported bus ratio (1/6
for the Dual-Core Intel® Xeon® Processor 5200 Series). When the TCC is activated,
the processor automatically transitions to the new frequency. This transition occurs
rapidly, on the order of 5 µs. During the frequency transition, the processor is unable to
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Table 2-3.
Thermal Specifications