Intel Core 2 Duo E7300 BX80570E7300 User Manual

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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. 

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 

V2.1 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.).  

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 

of this design guide. 

 

An overview of other BTX system considerations for thermal solutions can be 

obtained in the latest version of the Balanced Technology Extended (BTX) System 

. 

With the need to push 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