First point: that Antec fan is a 3-pin design, so the ONLY way to control its speed is for the mobo header to use the older Voltage Control Mode. Your mobo has ONE of its CHA_FAN headers as 3-pin (the one near front bottom edge) so it MAY do that type of fan control. (SOME mobos have a 3-pin header with NO speed control capability.) You have not told us exactly which CoolerMaster fan you have. Look closely at its female connector on the end of its wires. If it has THREE wires and holes, it is the same older type, and you CAN connect both of them to a single mobo header with a simple Splitter so that both have their speeds controlled. BUT if the CoolerMaster unit has FOUR wires and holes, it is a 4-pin PWM style that requires a different type on control signals. For that, you should connect it to the only 4-pin mobo CHA_FAN header near rear mid-board. The manual says that
header will automatically detect the fan type connected and control it properly.
If the Antec 3-pin fan IS speed controlled by the CHA_FAN2 3-pin header, then leave it there. If not - if it always runs full speed - post back here for a different arrangement.