Using a harness that splits into 4 female fan plugs (one primary with a tachometer and the others with no tachometer), a molex power and ground, and a 4 wire male fan plug that connects to the motherboard's CPU fan header, I have four identical delta fans running off my motherboard's CPU fan header's PWM control wire. Two fans are on the CPU heatsink and two fans are on the case. The tach wire that reports to the motherboard comes from the first heatsink fan, the other tachs are not connected to anything. The 12V Power and ground for all the fans come from the power supply's Molex 4 pin so the motherboard header is powering the fans at all, merely providing control and monitoring. Is there a limit I have exceeded as to how many fans I can run on this single PWM control pin? I could make more harnesses and run the two case fans on a separate header, just means more wires and molex plugs and making another fan curve, this is much simpler.