Biostar TForce 590 SLI Deluxe Setup Manual page 37

Start PWM Value
When CPU temperature arrives to the set value, the CPU fan will work
under Smart Fan Function mode. The range is from 0~127, with an
interval of 1.
Choices: 32 (default).
Slope PWM
Choices: 1 PWM Value/℃ (default), 2 PWM Value/℃, 4 PWM Value/℃, 8
PWM Value/℃, 16 PWM Value/℃, 32 PWM Value/℃, 64PWM Value/℃.
S1: CPU temperature is 60℃, and PWM value is 1 PWM/℃.
S2: CPU temperature is 60℃, and PWM value is 2 PWM/℃.
S3: CPU temperature is 60℃, and PWM value is 3 PWM/℃.
Increasing the value of slope PWM will raise the speed of CPU fan.
As in above diagram, when the CPU temperature reaches 60℃, the CPU
fan speed for 3 PWM/℃ is higher than 1 PWM/℃ (S1<S2<S3).
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