In the BIOS, Hard disks generally need to be set as AUTO, or detected using Detect drives and saved.
CD-ROM / DVD and Writers can normally be run as NONE or AUTO - if detected and saved, you may need to re-do if they are moved, as modes and settings may be incorrect.
Some people leave their IDE settings on full auto, but I find it can waste a second or 2, especially on unused ports - putting it into auto before moving drives around is a good idea though, as the autodetection gives you a rapid confirmation that all drives are accounted for.