What do you mean? Using a 3pin splitter to do 2x fans per? I would not see why this has anything to do with the pump, think of it like this, you are making a Electric Circuit, it goes in a circle, as long as your Motherboard ect. does what it should and supply a adequate amount of power to the header theres no reason the pump/fans should suffer. As we do know adding more to a circut can reduce performance, it would take alot to do so from a mobo/PSU together.