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7.3
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.
7.4
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
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 using 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
provides sufficient air flow to support the other system components.
Figure 7-5. Digital Thermal Sensor and Thermistor
74
®
QST Configuration and 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
Intel® Quiet System Technology (Intel® QST)
®
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
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