[juppy]

That's where the adaptor comes in. The adaptor has a 3 pin style plug on one end and a 4 pin molex style on the other end. So it turns a 3 pin into a 4 pin that will plug in to the power supply. When you get the flow-through type, it is the same thing except on the molex end it has another female connector on the back side of the male connector. In that, you can plug another fan in, and another into that one and so on, hence, the "daisy chain".