A PCI Express card with an inbuilt PWM fan controller and mounting points for an 80mm fan.
PCIce is available to buy on Tindie.
More information can be found on my website.
The hardware is based on an ATtiny13A which outputs a 25kHz PWM signal to the fan. A button is used for speed control, and the current speed is displayed on four multiplexed LEDs.
The firmware attempts to load the speed setting from EEPROM on boot. The speed setting is stored twice to guard against corruption. The second copy is inverted to detect a blank EEPROM. The speed will default to maximum if corruption is detected to prevent overheating. The button is debounced in software and must be released for a short period before the next press is registered.
The firmware can be compiled and flashed with the build script inside the firmware directory. This script expects an AVRISP MKII to be connected over USB. avr-gcc, avr-objcopy, avrdude and avr-libc are required to build the firmware.
PCIce is licensed under the GNU GPLv3 license. This license does not cover the use of Zoid Technology trademarks. A list of trademarks can be found here.