|If you have selected cd in bios and or boot menu and it doesn't work on known good disks then replace/reseat drive, cable and or power cable if on that. |
Othewise the drive adapter part of the motherboard is suspect.
Could try to boot from usb drive if needed maybe.
"Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10