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The Intel® Desktop Board D850GB contains 2 thermally controlled fan headers (FAN1 at J10A2 and FAN2 at J7M2 ) which are used to turn the fans on and off or adjust the fan speed as determined by the thermal sensors. This allows a system designer to develop a "Quiet PC" which only powers the fans enough to meet the current system cooling needs.
The Intel® Desktop Board D850GB fans are automatically controlled by hardware. Intel® Active Monitor allows sensor monitoring.
Ambient temperature of the Intel® Desktop Board D850GB system is thermally monitored by separate temperature sensors, which control voltage to each (FAN1 and FAN2) header. If the fan used provides a tachometer signal the sensor will report the fan speed to the ADM1031 controller.
The temperature sensors, which control the fans are initialized by the BIOS at system startup to turn on only when the sensor reaches 36 degrees Celsius (96.8 degrees Fahrenheit). The fans will shut down when their respective sensor cools down to 31 degrees Celsius (87.8 degrees Fahrenheit). This prevents the fans from turning off and on when the ambient air around the sensor fluctuates around 35-36 degrees Celsius (96.8 degrees Fahrenheit).
The following are power percentages based on the current ambient temperature as detected by the sensors:
- Fan starts only after reaching 36 degrees Celsius (96.8 degrees Fahrenheit)
- Fan stops only after dropping below 31 degrees Celsius (87.8 degrees Fahrenheit)
- Above 31 degrees Celsius (87.8 degrees Fahrenheit) and below 46 degrees Celsius (114.8 degrees Fahrenheit) the fan operates at 70% power.
- At or above 46 degrees Celsius (114.8 degrees Fahrenheit) the fan operates at 100% power.
If and when the fans does turn on they may appear slow because they start at 70 percent power and ramp to 100 percent power when the sensor reaches 46 degrees Celsius (114.8 degrees Fahrenheit).
There are no user controls for FAN3 (located at J6L1) and FAN4 (located at J3M1), however FAN3 is wired to the fan tachometer input of the SMSC LPC47M102 I/O controller. Neither FAN3 nor FAN4 are controlled by the thermal monitoring circuit.
All fans (FAN1, FAN2, FAN3, and FAN4) and the thermal control circuits are off during ACPI S3, S4, and S5 states. FAN3 and FAN4 along with the thermal control fan circuits are enabled during ACPI S0 and S1 states.
This applies to:
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