In principle, it is possible, but then I don't see the point of this controller. The Arduino Nano has 6 PWM outputs and when set to the appropriate frequency can directly drive up to 6 fans with a PWM control pin (fan with a 4 pin). Arduino can be permanently connected via USB and on this connection can be controlled by a program from Processing.
There is also lighting that I would like to control.
And each of the pins to the fan has
12 V
F (?Signal?)
GND
IN
5V
OUT
It would be enough to connect all the respective voltages and grounds together
I guess I could hook all the F which I assume is the pwm to the arduino. But would the fans work with a 3.3v from the Arduino?
And I would still have an issue with the lighting.
On writing this I realised I can probably use the controller I currently have and just snip the signal pins and wire pins and wire just those to the Arduino.
It would probably keep the whole thing cleaner.
I can see a wire that goes to a "IN" pin which is probably lights. And that I can probably do from the above github.