Mysterious "smart fan" settings in Foxconn motherboard BIOS

[Funny Bong]

I just installed a Foxconn 661FX7MJ motherboard, and I have a question about the BIOS settings. Under "PC Health Status", there are some settings that are enabled when I enable the smart fan control. They are PWM Start Temp, Start PWM Value, Slope PWM Value, Delta Temp. Does anyone know what these do? The manual wasn't much help, and neither was Google. I know they have something to do with the CPU fan speed, but I don't know exactly how they work. I have a 4-pin CPU fan, in case that matters.

Elias

 

[w00t]

it adjusts the fan speed according to temperatures

if the processor starts to heat up the fan speed will increase to cool the processor down

if the processor is cool it may decrease rpms on the fan to decrease noise

 

[Funny Bong]

I have a pretty good idea of what smart fan control and PWM are. I am just not clear about the meaning of these settings. I experimented with them, and here is what I found: Start PWM Value seems to influence how fast the fan spins when it is cold. PWM Start Temp seems to control at what temperature it starts to speed up. Slope PWM Value seems to control the amount of speed-up. Delta Temp doesn't seem to do anything. Does anyone know what that does?