Hi, I can't seem to find the right place to plug in to power cord from the fan to the mother board. The fan has a 3 pin plug with a place for a slide up the middle. There's one plug on the mother board that seems to be the right one but it is surrounded by a black plastic casing that doesnt allow the fan's plug to fit in. Please help and thanks in advance.
well dells proprietary connector is 3 pin, but it has a different wire pinout/location and the port is as you noticed surrounded by black plastic. the only option, as the others said, is a molex adapter
like this one http://www.newegg.com/Product/Product.aspx?Item=N82E168...
or if you are replacing the fan cause the orginal dell fan died, you can take the plastic end offthe old one and put it on the new one, just being careful to put all the wires in the right places.