Intel ® Qst Configuration & Tuning; Fan Hub Thermistor And Intel; Qst; Figure 25. Digital Thermal Sensor And Thermistor - Intel QX9770 - Core 2 Extreme Quad-Core Processor Design Manual

6.3 Intel
Initial configuration of the Intel QST is the responsibility of the board manufacturer.
The SPI flash should be programmed with the hardware configuration of the
motherboard and initial settings for fan control, fan monitoring, voltage and thermal
monitoring. This initial data is generated using the Intel provided Configuration Tool
At the system integrator the Configuration Tool can be used again but this time to
tune the Intel QST subsystem to reflect the shipping system configuration. In the
tuning process the Intel QST can be modified to have the proper relationships between
the installed fans and sensors in the shipping system. A Weighting Matrix Utility and
Intel QST Log program are planned to assist in optimizing the fan management and
achieve acoustic goal.
See your Intel field sales representative for availability of these tools.
6.4

Fan Hub Thermistor and Intel

There is no closed loop control between Intel QST and the thermistor, but they can
work in tandem to provide the maximum fan speed reduction. The BTX reference
design includes a thermistor on the fan hub. This Variable Speed Fan curve will
determine the maximum fan speed as a function of the inlet ambient temperature and
by design provides a Ψ
QST, by measuring the processor digital thermal sensor will command the fan to
reduce speed below the VSF curve in response to processor workload. Conversely if
the processor workload increases, the FSC will command the fan via the PWM duty
cycle to accelerate the fan up to the limit imposed by the VSF curve. Care needs to
be taken in BTX designs to ensure the fan speed at the minimum operating speed that
sufficient air flow is being provided to support the other system components.

Figure 25. Digital Thermal Sensor and Thermistor

62
®
QST Configuration & Tuning
sufficient to meet the thermal profile of the processor. Intel
CA
Variable Speed Fan (VSF) Curve Variable Speed Fan (VSF) Curve
Full Full
Speed Speed
Min. Min.
Operating Operating
LGA775 Socket Heatsink Loading
®

QST

Fan Speed Fan Speed
Operating Range Operating Range
with FSC with FSC
34 34
30 30
Inlet Temperature (°C) Inlet Temperature (°C)
§
Thermal and Mechanical Design Guidelines
100 % 100 %
Min % Min %
38 38