I've installed a replacement DVD Writer as well as a replacement DVD ROM drive. I believe that I've installed each drive correctly and have configured the jumper settings as per the diagrams on the drives. (I've tried slave/master, master/slave and cable). However, my computer doesn't recognise either drive when booted up. There is no listing under Device Manager for DVD or CD drives. Neither drive appears under My Computer. The drives are a Sony DDU 1613 DVD ROM and a LG GSA-4120B DVD writer. Both drives came without driver discs and I've downloaded firmware from manufacturer's websites. Can anyone suggest how I go about tackling this problem? Any help would be appreciated.