Intel Core 2 Duo E7300 BX80570E7300 User Manual

66  

 

Thermal and Mechanical Design Guidelines  

 

Fan to sensor 

Relationship

(Output Weighting Matrix)

Temperature sensing

and response

Calculations

(PID)

Fan Commands

(PID)

Fans

Temperature

Sensors

Intel

®

QST

System Response

PWM

PECI / SST

 

Intel QST provides an Output Weighting Matrix that provides a means for a single 

thermal sensor to affect the speed of multiple fans. An example of how the matrix 

could be used is if a sensor located next to the memory is sensitive to changes in both 

the processor heatsink fan and a 2

nd

 fan in the system. By placing a factor in this 

matrix additional the Intel QST could command the processor thermal solution fan and 

this 2

nd

 fan to both accelerate a small amount. At the system level these two small 

changes can result in a smaller change in acoustics than having a single fan respond 

to this sensor. 

The use of Proportional-Integral-Derivative (PID) control algorithms allow the 

magnitude of fan response to be determined based upon the difference between 

current temperature readings and specific temperature targets. A major advantage of 

a PID Algorithm is the ability to control the fans to achieve sensor temperatures much 

closer to the T

CONTROL

. 

7-2 is an illustration of the PID fan control algorithm. As illustrated in the 

figure, when the actual temperature is below the target temperature, the fan will slow 

down. The current FSC devices have a fixed temperature vs. PWM output relationship 

and miss this opportunity to achieve additional acoustic benefits. As the actual 

temperature starts ramping up and approaches the target temperature, the algorithm 

will instruct the fan to speed up gradually, but will not abruptly increase the fan speed 

to respond to the condition. It can allow an overshoot over the target temperature for 

a short period of time while ramping up the fan to bring the actual temperature to the