I can but it does not seem to matter. Radiator fan goes 100% all the time. Let me explain in more detail.
I have a total of 6 fans, and only 2 fan hubs in motherboard.
Cpu fan goes to cpu fan on mobo.
The other 5 go to the fan hub which is sata powered.
The ones that are in the hub are the aio pump, the vrm fan in the g12, the radiator fan, and 2 140mm phanteks fans. I would like to be able to adjust any of them, they however are not pwm, but if I could lower the voltage via sys fan that would work too, since they would go slower.