IBM Quad-Core Intel Xeon E5405 44R5630 User Manual

Quad-Core Intel® Xeon® Processor 5400 Series TMDG

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This section describes a procedure for measuring the load applied by the heatsink/clip/
fastener assembly on a processor package.

This procedure is recommended to verify the preload is within the design target range 
for a design, and in different situations. For example:

• Heatsink preload for the LGA771 socket.
• Quantify preload degradation under bake conditions.

This document reflects the current metrology used by Intel. Intel is continuously 

exploring new ways to improve metrology. Updates will be provided later as this 

document is revised as appropriate.

Three load cells are assembled into the base of the heatsink under test, in the area 
interfacing with the processor Integrated Heat Spreader (IHS), using load cells 
equivalent to those listed in 

To install the load cells, machine a pocket in the heatsink base, as shown in 

 

and 

. The load cells should be distributed evenly, as close as possible to the 

pocket walls. Apply wax around the circumference of each load cell and the surface of 
the pocket around each cell to maintain the load cells in place during the heatsink 
installation on the processor and motherboard.

The depth of the pocket depends on the height of the load cell used for the test. It is 
necessary that the load cells protrude out of the heatsink base. However, this 
protrusion should be kept minimal, as it will create an additional load offset since the 
heatsink base is artificially raised. The measurement load offset depends on the whole 
assembly stiffness (i.e. motherboard, clip, fastener, etc.). For example, the Quad-Core 
Intel® Xeon® Processor 5400 Series CEK Reference Heatsink Design clip and fasteners 
assembly have a stiffness of around 160 N/mm [915 lb/in]. If the resulting protrusion 
is 0.038 mm [0.0015”], then a extra load of 6.08 N [1.37 lb] will be created, and will 
need to be subtracted from the measured load. 

 shows an example using the 

Quad-Core Intel® Xeon® Processor 5400 Series CEK Reference Heatsink designed for 
the Quad-Core Intel® Xeon® Processor 5400 Series in the 771–land LGA package.

When optimizing the heatsink pocket depth, the variation of the load cell height should 

also be taken into account to make sure that all load cells protrude equally from the 

heatsink base. It may be useful to screen the load cells prior to installation to minimize 

variation.