Yes, it looks absurd to have so many optical drives in one system, but they happened to come one after the other. Since some among you is "eager" to know why these many, here is the story. When I bought my system, I had only Combo drive which worked pretty for a year. Slowly the CD writing ability of the combo drive failed while DVD cum reading abililty were retained. In those years I never thought I would ever have to write a DVD and when the combo drive could not be repaired I bought myself a CD writer. I could read DVDs on combo writer and write CDs on CD writer, it was wonderful. Then I bought a Dell laptop which could write even dual layered DVD, but as the warranty was about to expire the optical drive failed, first it failed to write CDs, then it failed to write DVDs. By then I had got used to burning DVDs and now I felt I am missing DVD writer. Since no help came from Dell and I needed a DVD writer urgently, I bought a DVD writer. But, the original combo drive still reads DVD, the CD writer works well so why should I discard them just because I have a new DVD writer? I did not want to offend their loyalty so I decided to retain all of them and use them. I would hereonwards use combo drive to read DVD, use CD writers for burning CD and the new DVD writer to burn DVDs only. Selling off the old ones would fetch me nothing, but by dividing the labour among the three drives, I would probably extend their lives too. Hope I am now clear (if not convincing).
Thank you guys for the help. I did the following: I used the 80-pin connector for the new DVD writer and the old CD writer on the secondary IDE port. I set the hard disk as master and combo drive as slave and connected them to the primary IDE port.
Thanks for support.