GIGABYTE GA-8AENXP-D - Manual (Page 43)

BIOS Setup - 43 -
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CPU Smart FAN Control
Disabled Disable this function.
Enabled Enable the CPU Smart FAN Control function. (Default value)
a. When the CPU temperature is higher than 65 degrees Celsius, CPU fan will
operate at full speed.
b. When the CPU temperature is between 20 and 65 degrees Celsius, the CPU
fan speed will change depending on the actual CPU temperature.
c. When the CPU temperature is lower than 20 degrees Celsius, CPU fan will stop
spinning.
CPU Smart FAN Mode
This option is available only when CPU Smart FAN Control is enabled.
Auto BIOS autodetects the type of CPU fan you installed and sets the optimal CPU Smart
FAN control mode for it. (Default value)
Voltage Set to Voltage when you use a CPU fan with a 3-pin fan power cable.
PWM Set to PWM when you use a CPU fan with a 4-pin fan power cable.
In fact, the Voltage option can be used for CPU fans with 3-pin or 4-pin power cables. However,
some 4-pin CPU fan power cables are not designed following Intel 4-wire fans PWM control
specifications. With such CPU fans, selecting PWM will not effectively reduce the fan speed.