Processor Thermal/Mechanical Information
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22
Thermal/Mechanical Design Guide
2.3.1 Heatsink
Size
The size of the heatsink is dictated by height restrictions for installation in a system and by the
amount of space available on the motherboard and other considerations for component height and
placement in the area potentially impacted by the processor heatsink. The height of the heatsink
must comply with the requirements and recommendations published for the motherboard form
factor of interest. Designing a heatsink to the recommendations may preclude using it in systems
adhering strictly to the form factor requirements, while still in compliance with the form factor
documentation.
For the ATX/microATX form factor, it is recommended to use:
•
The ATX motherboard keep-out footprint definition and height restrictions for enabling
components, defined for the platforms designed with the LGA775 socket in Appendix G of
this design guide.
•
The motherboard primary side height constraints defined in the
ATX Specification V2.1
and
the
microATX Motherboard Interface Specification V1.1
found at
.
The resulting space available above the motherboard is generally not entirely available for the
heatsink. The target height of the heatsink must take into account airflow considerations (for fan
performance for example) as well as other design considerations (air duct, etc.).
2.3.2 Heatsink
Mass
With the need for pushing air cooling to better performance, heatsink solutions tend to grow
larger (increase in fin surface) resulting in increased mass. The insertion of highly thermally
conductive materials like copper to increase heatsink thermal conduction performance results in
even heavier solutions. As mentioned in Section 2.1, the heatsink mass must take into
consideration the package and socket load limits, the heatsink attach mechanical capabilities, and
the mechanical shock and vibration profile targets. Beyond a certain heatsink mass, the cost of
developing and implementing a heatsink attach mechanism that can ensure the system integrity
under the mechanical shock and vibration profile targets may become prohibitive.
The recommended maximum heatsink mass for the Pentium 4 processor in the 775–land LGA
package is
450g
. This mass includes the fan and the heatsink only. The attach mechanism (clip,
fasteners, etc.) is not included.
2.3.3
Package IHS Flatness
The package IHS flatness for the product is specified in the processor datasheet and can be used
as a baseline to predict heatsink performance during the design phase.
Intel recommends testing and validating heatsink performance in full mechanical enabling
configuration to capture any impact of IHS flatness change due to combined socket and heatsink
loading. While socket loading alone may increase the IHS warpage, the heatsink preload
redistributes the load on the package and improves the resulting IHS flatness in the enabled state.
Summary of Contents for 640 - Pentium 4 640 3.2GHz 800MHz 2MB Socket 775 CPU
Page 14: ...Introduction R 14 Thermal Mechanical Design Guide ...
Page 38: ...Thermal Management Logic and Thermal Monitor Feature R 38 Thermal Mechanical Design Guide ...
Page 52: ...Intel Thermal Mechanical Reference Design Information R 52 Thermal Mechanical Design Guide ...
Page 60: ...Acoustic Fan Speed Control R 60 Thermal Mechanical Design Guide ...
Page 72: ...Heatsink Clip Load Metrology R 72 Thermal Mechanical Design Guide ...
Page 99: ...Mechanical Drawings R Thermal Mechanical Design Guide 99 Figure 50 Reference Fastener Sheet 1 ...
Page 103: ...Mechanical Drawings R Thermal Mechanical Design Guide 103 Figure 54 Clip Heatsink Assembly ...
