Processor Thermal/Mechanical Information
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Thermal/Mechanical Design Guide 19
Figure 2. Processor Case Temperature Measurement Location
37.5 mm
Measure T
C
at this point
(geometric center of the package)
37.5 mm
37.5 mm
Measure T
C
at this point
(geometric center of the package)
37.5 mm
2.2.2 Thermal Profile
The Thermal Profile defines the maximum case temperature as a function of processor power
dissipation. The TDP and Maximum Case Temperature are defined as the maximum values of the
thermal profile. By design the thermal solutions must meet the thermal profile for all system
operating conditions and processor power levels.
The slope of the thermal profile was established assuming a generational improvement in thermal
solution performance of about 10% based on previous Intel reference designs. This performance
is expressed as the slope on the thermal profile and can be thought of as the thermal resistance of
the heatsink attached to the processor,
Ψ
CA
(Refer to Section 3.1). The intercept on the thermal
profile assumes a maximum ambient operating condition that is consistent with the available
chassis solutions.
To determine compliance to the thermal profile, a measurement of the actual processor power
dissipation is required. Contact your Intel sales representative for assistance in processor power
measurement. The measured power is plotted on the Thermal Profile to determine the maximum
case temperature. Using the example in
Figure 3 for a processor dissipating 70 W the maximum
case temperature is 61 °C.
For the Pentium 4 processor in the 775–land LGA package, there are two thermal profiles to
consider. The Platform Requirement Bit (PRB) indicates which thermal profile is appropriate for
a specific processor. This document will focus on the development of thermal solutions to meet
the thermal profile for PRB=1. See the processor datasheet for the thermal profile and additional
discussion on the PRB.
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