Disconnect all power Disconnect the dvd drive power/IDE cable (ribbon) Remove the 4 or 2 screws securing it in the case Remove the dvd drive On the rear of the unit you will see, a small area that contains 6 pins (3 on top, 3 on bottom). On of these pairs will have a jumper across 2 of the pins. On the top of the drive/or rear there should be a little note/lable/imprint saying as follows: MAS = Master SLA = Slave CSL = Cable Select Link The jumper pertaining to the connected position will mean whether it is master/slave or cable select. Just move the jumper to your desired location. Hope this helps.............