Just got 2 of these 120mm fans and I'm wondering what the supplied power connector adapter is designed for. The fan itself has a tri-connection plug that's evidently designed for a MB case fan connection. The supplied adapter will connect to the fan's plug and that can go to a 12v molex, and from that supply 12v to another 12v molex supplied device. But there's a 3 pin connector coming off that has only one wire attached and looks designed to plug into a MB case fan connector. Is the idea somehow to support controlling the fan speed from the MB? I don't understand that. If you were going to do that why wouldn't you just plug the fan into that?