That said, let's move on and have a look at the basic concepts behind SpeedFan's Advanced Fan
Controllers. A Fan Controller links a specific PWM control (the Controlled Speed) to the current
value of any number of source temperatures. For each temperature we can define the response curve.
This means that we can define what PWM value we want to apply for every temperature value. Each
temperature can have a different response. Let's see how to create our own first Fan Controller.
Start SpeedFan, press CONFIGURE button and select the Fan Control tab. Enlarge the window if
needed. In the example image we have already created a Fan Controller and called it "CPU Fan
Control Strategy". We can create more using the Add button on the right. With the Remove button
we can delete a fan controller we previously created. As soon as we select "CPU Fan Control
Strategy" in the list box, its parameters will appear below in the window. A Fan Controller
requires a PWM to act on. Multiple temperatures can be used to control the PWM. For each
temperature is defined its response curve. The final value applied to the controlled PWM
depends on the selected method: either MAX of speeds
or SUM of speeds
. When a
temperature is selected in the list box, the relevant configuration parameters appear on the
The response curve determines the requested PWM value (ranging from 0% to 100%) depending on
the current temperature. By using the "<" and ">" buttons, the minimum and the maximum
temperature levels can be selected. If the current temperature is below the minimum, the
selected PWM value will be the one assigned to the minimum temperature. If the current
temperature is higher than the maximum, the selected PWM value will be the one assigned
to the maximum temperature. The hysteresis
value is used to avoid fan fluctuations.
In a few words, when the temperature rises, the new PWM value is applied immediately. When
it lowers, the last applied PWM value is kept until the current temperature is hysteresis
degrees lower than the temperature that caused the current PWM to be applied.