Intel Core 2 Duo E7300 BX80570E7300 User Manual

Thermal and Mechanical Design Guidelines   

 21 

T

CONTROL 

will dissipate more power than a part with lower value (farther from 0, e.g. 

larger negative number) of T

CONTROL 

when running the same application.  

This is achieved in part by using the 

CA

 vs. RPM and RPM vs. Acoustics (dBA) 

performance curves from the Intel enabled thermal solution. A thermal solution 

designed to meet the thermal profile would be expected to provide similar acoustic 

performance of different parts with potentially different T

CONTROL

 values.  

The value for T

CONTROL

 is calculated by the system BIOS based on values read from a 

factory configured processor register. The result can be used to program a fan speed 

control component. See the appropriate processor datasheet for further details on 

reading the register and calculating T

CONTROL

. 

See Chapter 

7, Intel

 QST), for details on 

implementing a design using T

CONTROL

 and the Thermal Profile. 

To remove the heat from the processor, three basic parameters should be considered:  

 

The area of the surface on which the heat transfer takes place. Without any 

enhancements, this is the surface of the processor package IHS. One method used 

to improve thermal performance is by attaching a heatsink to the IHS. A heatsink 

can increase the effective heat transfer surface area by conducting heat out of the 

IHS and into the surrounding air through fins attached to the heatsink base.  

 

The conduction path from the heat source to the heatsink fins. Providing a 

direct conduction path from the heat source to the heatsink fins and selecting 

materials with higher thermal conductivity typically improves heatsink 

performance. The length, thickness, and conductivity of the conduction path from 

the heat source to the fins directly impact the thermal performance of the 

heatsink. In particular, the quality of the contact between the package IHS and 

the heatsink base has a higher impact on the overall thermal solution performance 

as processor cooling requirements become stricter. Thermal interface material 

(TIM) is used to fill in the gap between the IHS and the bottom surface of the 

heatsink, and thereby improve the overall performance of the stack-up (IHS-TIM-

Heatsink). With extremely poor heatsink interface flatness or roughness, TIM may 

not adequately fill the gap. The TIM thermal performance depends on its thermal 
conductivity as well as the pressure applied to it. Refer to Section 

Appendix C for further information on TIM and on bond line management between 
the IHS and the heatsink base. 

 

place. Convective heat transfer occurs between the airflow and the surface 

exposed to the flow. It is characterized by the local ambient temperature of the 

air, T

A

, and the local air velocity over the surface. The higher the air velocity over 

the surface, and the cooler the air, the more efficient is the resulting cooling. The 

nature of the airflow can also enhance heat transfer  using convection. Turbulent 

flow can provide improvement over laminar flow. In the case of a heatsink, the 

surface exposed to the flow includes in particular the fin faces and the heatsink 

base. 

Active heatsinks typically incorporate a fan that helps manage the airflow through 

the heatsink.