Fan Control is a Windows utility for controlling supported CPU, graphics-card and case fans. It connects temperature readings to fan-speed rules, allowing different parts of a PC’s cooling system to respond to the same workload. A case fan, for example, can follow curves based on both CPU and GPU temperatures instead of responding to just one component.
Fan calibration
Fan Control separates a fan’s control channel from its speed reading. Pairing the control with the appropriate speed sensor, either manually or through automatic pairing, lets the program relate commands to the fan’s actual rotation. Calibration then finds starting and stopping points, minimum and maximum speeds, and the relationship between power percentage and RPM.
That calibration allows a curve to request a target RPM rather than a power percentage. Start and stop settings handle the transition between a stationary and rotating fan, while a minimum setting puts a floor under the control output. Separate step-up and step-down limits govern how quickly the output can rise or fall. Calibration avoid points can exclude particular settings at which a fan rattles or produces unwanted noise.
Temperature curves
A linear curve maps a chosen temperature range to a speed range, applying the minimum speed below the lower temperature and the maximum above the upper temperature. For a more detailed response, the graph editor lets users add points and change their temperature and speed coordinates. Hysteresis requires a minimum temperature change before the output changes; response time adds a time condition. These settings determine how readily a fan follows fluctuating readings.
Other curve types use different control logic. Trigger switches between idle and load speeds at separate temperature thresholds, holding the current speed until the opposite threshold is reached. Flat supplies a fixed percentage that can be assigned to multiple fans. Auto adjusts speed using the temperature trend to approach a selected load temperature. Its feedback loop is suited to a sustained load; it is less suited to workloads that keep changing.
Curve mixing
Fan Control can combine existing curves so that one fan responds to more than one temperature source. A maximum mix of a CPU curve and a GPU curve sends the higher of their requested speeds to the assigned fan. This lets either component increase case airflow. Minimum, average, sum and subtraction functions offer other ways to combine the curve outputs.
Sync handles a different task: it copies the percentage of a selected control. Fans assigned to that sync curve follow changes to the original control, including a newly assigned curve. An optional absolute or proportional offset lets the following controls run at a different percentage without maintaining separate temperature rules.
Sensor inputs
Curves can use temperature readings from supported processors, graphics cards, motherboards and drives. Custom sensors change those inputs before a curve uses them. Time Average calculates a reading over a selected period, while Mix Sensor combines several temperature readings using a selected mathematical function. Offset adjusts a sensor by a fixed number of degrees or a percentage.
For an external temperature source, a file sensor reads a Celsius value from the first line of a .sensor text file. Plugins can extend Fan Control with additional temperature readings, speed sensors or control channels.
Actual device support depends on the hardware interfaces exposed through the program’s backend and the relevant plugin. Most laptops do not expose their fans through the same interfaces as desktop motherboards, although some models have dedicated plugins.
Fan Control on NVIDIA and AMD cards
Graphics-card firmware still affects the available fan behavior. Modern NVIDIA RTX cards impose minimum running-speed limits, and Fan Control releases its control at a zero-percent command so the card can use its own fan-stop logic. Whether the fans actually stop depends on the card’s temperature, power and other native conditions. Multiple physical fans may also share a control channel.
AMD cards have their own minimum-speed and zero-RPM conditions. Applying fan settings through Fan Control resets Adrenalin overclocking tuning to its defaults; using the temperature readings alone does not cause that reset.
Cooling profiles
Fan Control can save, edit and load multiple profiles, keeping different cooling rules available without rebuilding their curves. A command-line option can select a configuration file or switch the configuration in an already running instance. The program can also run as a service at boot, allowing its fan controls to operate before a user signs in.
