Intel
®
Celeron
®
D Processor in the 775-Land LGA Package Thermal Design Guide21
Order #303730
Thermal Metrology
• If a variable speed fan is used, it may be useful to add a thermocouple taped to the barrier
above the location of the temperature sensor used by the fan to check its speed setting against
air temperature. When measuring T
A
in a chassis with a live motherboard, add-in cards, and
other system components, it is likely that the T
A
measurements will reveal a highly
non-uniform temperature distribution across the inlet fan section.
Note: Testing an active heatsink with a variable speed fan can be done in a thermal chamber to capture
the worst-case thermal environment scenarios. Otherwise, when doing a bench top test at room
temperature, the fan regulation prevents the heatsink from operating at its maximum capability. To
characterize the heatsink capability in the worst-case environment in these conditions, disable the
fan regulation and power the fan directly, based on guidance from the fan supplier.
NOTE: Dimensions in drawing not to scale.
3.3.2 Measuring Passive Heatsinks
•
Thermocouples should be placed approximately 13 to 25 mm [0.5 to 1.0 in.] away from
processor and heatsink as shown in Figure 6. The thermocouples should be placed
approximately 51 mm [2.0 in.] above the baseboard. The dimension above the baseboard will
vary depending on the maximum height in the intended form factor. This placement guideline
is meant to minimize the effect of localized hot spots from baseboard components.
Figure 5. Measuring T
LA
— Active Heatsink
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