Definition
A fan curve is the relationship between a cooling fan's speed and a control input, almost always chip temperature, defined in a miner's firmware. As an ASIC heats up, the curve dictates how aggressively the controller ramps the fans; as it cools, the curve lets them throttle back. It is the logic that turns a temperature reading into a PWM duty-cycle command sent to the fan.
How it works
The control board continuously reads on-board temperature sensors. When measured chip temperature crosses a preset upper threshold, the controller raises the pulse-width-modulation (PWM) signal to spin the fans faster and pull more heat away. When temperature falls below a lower threshold, it reduces PWM to slow the fans, cutting noise and power. The shape of the curve, where it starts ramping and how steeply, determines whether a miner runs cool and loud or quiet and warm.
Why it matters for operators
A poorly matched fan curve is a common, avoidable cause of trouble. Too lazy a curve lets chips drift toward thermal limits and triggers protective throttling; too aggressive a curve wastes power and drowns a home in noise. Firmware updates frequently ship revised curves, and tuning-focused firmware exposes the curve directly so operators can balance acoustics, longevity, and hashrate for their environment. Fans engineered for high static pressure are what make an aggressive curve effective inside dense heatsinks.
For the protective fallback and the airflow concept the curve relies on, see Thermal Throttling and Static Pressure.
In Simple Terms
A fan curve is the relationship between a cooling fan’s speed and a control input, almost always chip temperature, defined in a miner’s firmware. As…