Case fan has both 3 pin plug and molex plug, which do I plug in?

[hedfun2]

A recently bought a case in which all the fans inside have both a 3 pin connector and a molex connector. The motherboard I have has several 3 pin fan headers too. Should I plug in both the molex and the 3 pin fan connector or just the 3 pin?

 

[Dark Lord of Tech]

Just the 3 pin is fine , use molex if you don't have any headers left on the board.

 

[Herobrine]

With Molex connector the fan will spin with max speed. 3pin (if supports voltage control) might run quieter . 3pin goes to motherboard or fan controller while Molex to PSU.