If you want to run it on two PSUs, there's a risk of the controller PSU shutting down and the boards on the other PSU overheating. If I was running a 750 and a 1300, I'd hook the controller and two boards off the 1300 and the third board off the 750. I would then wire one of the fans to run off the 750, except you need to keep the blue and yellow wires from the fan tied into the controller so it still has speed control and RPM readings. But what'll happen is, worst case, your 1300 shuts off and you still have one board making heat but you still have one fan to cool it.