FanCtrl: automatic fan curves for a PC, with hardware and AIO support

A Windows utility that maps sensors to fan curves

FanCtrl is software that allows you to automatically control the fan speed on your PC. The main window shows temperature, fan speed and fan control, and the percentage of the fan control can be changed directly to control the PWM, with the README noting that this manual value is not saved, which is the point of the automatic mode. Each item can be renamed so the graph and the list read the way you want. The audience is a Windows user with a heatsink or an AIO cooler who wants a temperature curve rather than the BIOS default, and who is comfortable installing a second utility alongside their graphics driver tools. The requirements are short but specific, and they set the boundaries of the project: the .NET framework 4.7.2, the Visual redistributable 2019 for x64, and, if you want the on-screen display, Rivatuner Statistics Server installed and running.

The supported hardware list, and what sits behind it

The support section names motherboards generally, and then names specific hardware: the NZXT Kraken, the EVGA CLC, the NZXT RGB and Fan Controller, and liquidctl. The reason for that list is in the section on external libraries, which names the component behind each capability. Sensor and fan control comes from LibreHardwareMonitorLib, which is the LibreHardwareMonitor project, and NVIDIA graphics card sensor and fan control comes from NvAPIWrapper, which is also what the option panel calls the NVIDIA graphics card control library. NZXT Kraken USB communication goes through HIDSharp, and EVGA CLC USB communication through SiUSBXp or libusb-1.0. The remaining dependencies are unglamorous and worth knowing: Newtonsoft Json for JSON, ZedGraph for the graph, and liquidctl for the liquidctl plugin. So the hardware list is really a list of which USB and driver protocols the project has wired up.

The options panel, where the integration choices live

The option list is effectively the configuration surface, and each entry is a switch. LibreHardwareMonitor can be used or not, and you can choose which devices are required for control. NvAPIWrapper can be added to control the NVIDIA card. HWiNFO is communicated with to get sensor temperature and fan RPM. There are toggles for language, with English, Korean, Japanese, French, Spanish, Russian and Chinese, and the repository carries a Language.xlsx file for that. The tray icon animation starts when automatic fan control is checked, which is a small piece of feedback that tells you the automation is actually engaged. Fahrenheit can be set for the temperature display. The program can start minimized, start with Windows for auto-run at Windows start, and there is a delay in seconds before that auto-run. The Reset option initialises all settings and libraries, which is the button to reach for when something is behaving oddly.

Auto fan control: modes, hysteresis, step and presets

The automatic control section is the substance of the tool. You check the box to enable it, select the temperature sensor to target, add the fan to control, and pick from the list to display the graph, adjusting the graph accordingly. Mode has only four names and the README notes that they must be set separately, which is a hint that this is where the behaviour is decided rather than a cosmetic choice. Preset lets you save or load the current graph setup state, so a working curve survives a restart. Unit changes the unit of temperature and the PWM percentage, with steps of 1, 5 or 10. Hysteresis exists so that when the temperature drops, the PWM changes only after the temperature falls further, which is the mechanism that stops a fan from oscillating around a threshold. Step decides whether the graph setting is step or linear. Auto leaves the fan control in the BIOS default state up to the set temperature, and the README limits that option to LibreHardwareMonitor, OpenHardwareMonitor, Gigabyte and NvAPIWrapper. When you click Apply and OK the settings are saved as a file, and the program reads from that file on the next run.

The on-screen display rides on Rivatuner Statistics Server

The on-screen display is the feature that distinguishes FanCtrl from a plain fan curve utility, and it is built on someone else's software. The README states that the OSD feature must have Rivatuner Statistics Server installed and running, and the section repeats the requirement. Within that, GROUP stands for one line and ITEM is the data to display, which is a small vocabulary for a lot of possible overlays. The lighting section works the same way, with the lighting packets linked per device: an X2 packet for the NZXT Kraken X2, an X3 packet for the Kraken X3, a clc packet for the EVGA CLC and an RGBnFC packet for the NZXT RGB and Fan Controller, all stored in a Packet directory in the repository. The example shows the range available, with a spectrum wave for the logo and the ring on the X2, and a fading logo with a pulsing ring elsewhere. The liquidctl and Plugins sections both link out to their own usage documents rather than duplicating them.

Precautions, the GPLv3 licence and the release history

The precautions section is the part of this README a prospective user should read twice. FanCtrl is free software with a GNU GPLv3 licence, and the README says you can malfunction while other fan control programs are on at the same time. The author is not responsible for hardware that has failed or is not working using this software, and not all types of hardware are supported. Those are honest limits for a tool that writes to fan headers and talks to coolers over USB. The repository layout is a C# Visual Studio project, with a FanCtrl.sln, an App.config, a Properties and Resources directory, a dll directory for the bundled libraries, a preset directory, a plugin directory and a Plugin.md describing the plugin interface, along with a Korean README. The release history shows steady work: v1.7.8 on 2025-11-26, v1.7.9 on 2026-04-16 and v1.8.0 on 2026-08-29, with the last push on the same day as that tag, so the project is still being changed rather than parked.

Editorial conclusion

FanCtrl fits a Windows user with an NZXT Kraken, an EVGA CLC, an NZXT RGB and Fan Controller, or a plain motherboard who wants a fan curve tied to a sensor and an on-screen display of temperature and RPM. It does not fit a Linux user, a Mac user, or someone whose hardware is not in the supported list, and it does not fit a machine where another fan control utility is already running. Before installing, check that your specific cooler or board is supported, install the Rivatuner Statistics Server if you want the OSD, and read the precautions section, because the project states plainly that you can malfunction while other fan control programs are running.

Frequently asked questions

Official sources

1. Issues
2. License: GPL-3.0
3. lich426/FanCtrl on GitHub
4. README
5. Releases