Leave it to DELL to take a simple procedure & screw it up. I have replaced & added many hard drives on DELL desktops and other MFG's, But this is the 1st time on this Optiplex Desktop which I just inherited. In order to add a 2nd drive, one must first move the primary (original drive) to the right, in the bay. Then insert the 2nd drive to the left where the original drive was, thus allowing the connector for the cable to face downward to make the connection.
Again, I say WTF ! !