Thermal Monitor 2 - Intel Quad-Core Xeon Datasheet

Thermal Specifications
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 the TM1 is enabled, and a high temperature situation exists (that is, TCC is
active), the clocks will be modulated by alternately turning 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 Quad-Core Intel® Xeon® Processor E5300
Thermal Profile, the Quad-Core Intel® Xeon® Processor L5300 Series Thermal Profile,
Quad-Core Intel® Xeon® Processor X5365 Series Thermal Profile, or Quad-Core
Intel® Xeon® Processor X5300 Series 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 Quad-Core Intel® Xeon® Processor X5300 Series 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 Quad-Core Intel®
Xeon® Processor 5300 Series Thermal/Mechanical Design Guidelines for information on
designing a thermal solution.
The duty cycle for the TCC, when activated by the TM1, is factory configured and
cannot be modified. The TM1 does not require any additional hardware, software
drivers, or interrupt handling routines.
6.3.3

Thermal Monitor 2

The Quad-Core Intel® Xeon® Processor 5300 Series adds support for an Enhanced
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 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.
A processor enabled for TM2 includes two operating points, each consisting of a specific
operating frequency and voltage, which is identical for both processor dies. 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 Quad-Core Intel® Xeon® Processor 5300 Series). When the TCC is activated,
the processor automatically transitions to the new frequency. This transition occurs
Quad-Core Intel® Xeon® Processor 5300 Series Datasheet
Table 2-3.
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