LGA775 Socket Heatsink Loading
20
Thermal and Mechanical Design Guidelines
Passive heatsink solutions require in-depth knowledge of the airflow in the chassis.
Typically, passive heatsinks see lower air speed. These heatsinks are therefore
typically larger (and heavier) than active heatsinks due to the increase in fin surface
required to meet a required performance. As the heatsink fin density (the number of
fins in a given cross-section) increases, the resistance to the airflow increases: it is
more likely that the air travels around the heatsink instead of through it, unless air
bypass is carefully managed. Using air-ducting techniques to manage bypass area
can be an effective method for controlling airflow through the heatsink.
2.3.1
Heatsink Size
The size of the heatsink is dictated by height restrictions for installation in a system
and by the real estate 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 system 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
V2.2 and the microATX Motherboard Interface Specification V1.2 found at
http://www.formfactors.org/
.
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.).
For BTX form factor, it is recommended to use:
•
The BTX motherboard keep-out footprint definitions and height restrictions for
enabling components for platforms designed with the LGA77 socket in
Appendix G
of this design guide.
•
An overview of other BTX system considerations for thermal solutions can be
obtained in the Balanced Technology Extended (BTX) System Design Guide v1.0
found at
http://www.formfactors.org/
.
2.3.2
Package IHS Flatness
The package IHS flatness for the product is specified in the 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 QX68000 Core 2 Extreme
Page 30: ...LGA775 Socket Heatsink Loading 30 Thermal and Mechanical Design Guidelines...
Page 74: ...Heatsink Clip Load Metrology 74 Thermal and Mechanical Design Guidelines...
Page 76: ...Thermal Interface Management 76 Thermal and Mechanical Design Guidelines...
Page 96: ...Case Temperature Reference Metrology 96 Thermal and Mechanical Design Guidelines...
Page 108: ...Legacy Fan Speed Control 108 Thermal and Mechanical Design Guidelines...
Page 112: ...BTX System Thermal Considerations 112 Thermal and Mechanical Design Guidelines...
