right if it has a pos and neg wire your still going to need the y power splitter. connect it to the end of the normal power that goes into ur hdd and connect one of the two available cords back into ur hdd. now im assuming the wires on the xlight are red and black? if they what you need to do is wire them into the red and black wires of the 4pin molex (there are two black wires on the molex but either will do), the other black and the yellow dont matter. hopefully if you hav done it right, you should hav it looking like this. i know the image is crap but it should help somehow.