64-bit Intel Xeon Processorwith up to 8MB L3 Cache Thermal/Mechanical Design Guidelines

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Thermal/Mechanical Reference Design
64-bit Intel
®
Xeon™ Processor MP with 8 MB L3 Cache 11
Thermal/Mechanical Design Guidelines
Figure 2-2. Critical Interface Dimensions (Sheet 2 of 2)
2.2 Thermal Requirements
In order to remain within a certain case temperature (T
CASE
) specification to achieve optimal
operation and long-term reliability, the thermal specification methodology, referred to as the thermal
profile, is used. The intent of the thermal profile specification is to support acoustic noise reduction
through fan speed control and ensure the long-term reliability of the processor.
To ease the burden on thermal solutions, the Thermal Monitor feature and associated logic have
been integrated into the silicon of the processor. By taking advantage of the Thermal Monitor
feature, system designers may reduce thermal solution cost by designing to Thermal Design Power
(TDP) instead of maximum power. The TDP is defined as the power level at which the processor
thermal solutions be designed to dissipate. TDP is not the maximum power that the
processor/chipset can dissipate. TDP is based on measurements of processor power consumption
while running various high power applications. This data set is used to determine those applications
that are interesting from a power perspective. These applications are then evaluated in a controlled
thermal environment to determine their sensitivity to activation of the thermal control circuit. This
data set is then used to derive the TDP targets published in the processor datasheet. Thermal
Monitor can protect the processor in rare workload excursions above TDP. Therefore, thermal
solutions should be designed to dissipate this target power level.
The relationship between TDP to the thermal profile, and thermal management logic and thermal
monitor features, is discussed in the sections to follow. The thermal management logic and thermal
monitor features are discussed in extensive detail in the processor Datasheet.
2.2.1 Thermal Profile
The thermal profile is a linear line that defines the relationship between a processor’s case
temperature and its power consumption as shown in Figure 2-3. The equation of the thermal profile
is defined as:
y = ax + b Equation 1