Intel740™ Graphics Accelerator Thermal Design Considerations
10 Application Note 653
4.1.5.2 Vent Shape
Round, staggered pattern openings are best for EMI containment, acoustics and airflow balance.
For material related to EMI considerations please see the Pentium II Processor EMI Design
Guidelines Application Note.
4.1.6 Ducting
Ducts can be designed to isolate components from the effects of system heating and to maximize
the thermal budget. Air provided by a fan or blower could be channeled directly over the Intel740
graphics accelerator and card or split into multiple paths to cool multiple components.
4.1.6.1 Ducting Placement
When ducting is to be used, it should direct the airflow evenly from the fan across the entire
component and surrounding motherboard. The ducting should be accomplished, if possible, with
smooth, gradual turns as this will enhance the airflow characteristics. Sharp turns in ducting should
be avoided. Sharp turns increase friction and drag and will greatly reduce the volume of air
reaching the Intel740 graphics accelerator and card.
4.2 Thermal Enhancements
One method used to improve thermal performance is to increase the surface area of the device by
attaching a metallic heat sink to the mold cap. To maximize the heat transfer, the thermal resistance
from the heat sink to the air can be reduced by maximizing the surface area of the heat sink itself.
For users whose ambient environments exceed 55°C, a Fan Heat Sink is strongly recommended to
effectively cool the Intel740
graphics accelerator
(discussed in Section 4.2.2, “Low Profile Fan
Heat Sink” on page 11).
Note: Increasing the heat flow through the case increases the difference in temperature between the
junction and case, reducing the maximum allowable case temperature.
4.2.1 Clearance
Though each design may have unique mechanical volume and height restrictions or
implementation requirements, the constraints typically placed on the Intel740 graphics accelerator
by an adjacent PCI Card is 0.450” clearance between the Intel740 graphics accelerator mold cap
and the back of the adjacent PCI Card.
Note: If the heat sink selected is larger than 35 mm x 35 mm, the maximum component height under the
portion of the heat sink overhaning the board is 0.09 inches.
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