Intel 5400 Series - Manual (Page 24)

Thermal/Mechanical Reference Design
24 Quad-Core Intel® Xeon® Processor 5400 Series TMDG
2.2.5 Thermal Profile
The thermal profile is a line that defines the relationship between a processor’s case
temperature and its power consumption as shown in
Figure 2-7 . The equation of the
thermal profile is defined as:
Equation 2-1.y = ax + b
Where:
y = Processor case temperature, T
CASE
(°C)
x = Processor power consumption (W)
a = Case-to-ambient thermal resistance, ΨCA (°C/W)
b = Processor local ambient temperature, TLA (°C)
The high end point of the Thermal Profile represents the processor’s TDP and the
associated maximum case temperature (T
CASE_MAX
) and the lower end point represents
the local ambient temperature at P = 0W. The slope of the Thermal Profile line
represents the case-to-ambient resistance of the thermal solution with the y-intercept
being the local processor ambient temperature. The slope of the Thermal Profile is
constant, which indicates that all frequencies of a processor defined by the Thermal
Profile will require the same heatsink case-to-ambient resistance.
In order to satisfy the Thermal Profile specification, a thermal solution must be at or
below the Thermal Profile line for the given processor when its DTS temperature is
greater than T
CONTROL
(refer to Section 2.2.6 ). The Thermal Profile allows the
customers to make a trade-off between the thermal solution case-to-ambient
resistance and the processor local ambient temperature that best suits their platform
implementation (refer to
Section 2.4.3 ). There can be multiple combinations of thermal
solution case-to-ambient resistance and processor local ambient temperature that can
meet a given Thermal Profile. If the case-to-ambient resistance and the local ambient
temperature are known for a specific thermal solution, the Thermal Profile of that
solution can easily be plotted against the Thermal Profile specification. As explained
Figure 2-7. Thermal Profile Diagram