Lets say you have 2x 120mm Fans on your CPU Heatsink is it ok to use a splitter and plug the fans into 1 header on the Fan Controller? (2x Noctua Fans) I think the controller is listed for 10w per channel.
10 W/12 V: 0.83 A
Lets take Gelid WING 12 UV Blue: Current (A): 0.22 (means about 2.64 watt)
Give it some head room and you still can plug in 3 of them.