I have a neo 2 and found that it has a sound from the fan, but i also noticed that the fan behaves weird.
It stops/start sometimes and then continous to spin, and the sound that the fan or electric controller makes seems to follow the stop/start procedure.
It's only the fan closest to the bottom bracket that behaves like this.
Don't know if it's normal? What do you think?
I have a link to a video here, please use headphones: