First, why do you want to pug into the MB, is it for speed control?
If you do want to plug into the motherboard, please not that 4 pin(molex style, not pwm) fans will not give you a speed reading as those tend to just have 2 wires(+/-).
The adapter listed above is one of the BEST pwm splitters you can get, but I am not sure what you are looking for.
That adapter gets power from the computer power supply, speed control from the motherboard and allows one of the 3 fans speeds to be monitored.
I say it is a good adapter because many of those adapters actually connect both(or 3) fans speed sensing wire(yellow on most fans, green for Coolermaster blade master) together. That can cause misreadings of fan speed since the board sees the speed of 2 fans on 1 plug.
The listed adapter will also allow you to run 3 fans at full speed(PWM or 3Pin) off the power supply if you do not connect the motherboard cable(or turn off speed control). You need PWM fans for speed control with that adapter.
You may well be looking at something like this as well(if fan speed monitoring is not needed).It lets you use fans at 3 speeds(the 7 volt uses a resistor, that is safer for some power supplies). All 3 plugs can be used at once if you want as well.