Check Cooing Fan Assemble Guidance for details.
When we designed Khadas VIM, our team talked about is it necessary to add the control circuit for cooling fan, we final didn’t design with it as we tested the temperature was not high when playing 4K videos on Android. It turned out we made a wrong decision, many users used VIM as Linux server which require more stable device with cooling fan for better heat spread.
So, currently, the cooling fan still can’t be controlled by GPIO, except we design a new module with the power management and can be controlled by the GPIO then.