K

Y-connectors work, just make sure that they are 4-pole at all ends, otherwise the fan may rotate too high from the control unit and become loud. Mixing 4 and 3 poles on one line is not ideal via the control unit.

I also have the Commander PRO, if you don't mind that 3 fans rotate at the same speed as 3 others (Y-cable) then it is possible, but it can probably happen that 3 PIN fans overload the Commander output if too many (several Y-cables) are used. With 4 PIN fans you won't have any problems, as one of the 4 pins is only for the speed signal (PWM signal), so you could theoretically connect 100 fans in parallel. The only disadvantage is, when using Y cables, even with 4 pin fans, that you only get the speed signal from one fan into the Commander. See -> Google -> pc fan pinout