I have been figuring out the extensive BIOS options for the boot sequence, while fitting an empty SATA harddisk in a ThinkCentre S50. The trouble is that the S50 does not seem detect an IDE optical drive
(The SATA HDD drive is the only device in the detected IDE list)
The IDE CDROM drive was selected by jumper to Slave, with no Master present.
If you have a situation with a SATA harddisk present and one IDE CDROM drive, be sure to not set the jumper to Slave.
Typically, if a single IDE device is installed per controller, that device must be set to master.
The S50 has two IDE controllers and if a if two devices are attached to one controller, then one would be master and the other slave.