|You didn't specify but I suspect that both your hard drive and CD drive are IDE type and are both connected to the same cable. |
Is that correct?
If so, then you may have the jumpers on the back of each drive set incorrectly. Other possibilities include a bad cable, no power cables connected to the drives, or the controller disabled in the BIOS.
I just looked at your "new" motherboard. That board is 8 years old. That said, below is an excerpt from page 38 of the manual for that board.
1st Boot Dev ice : Floppy
2nd Boot Dev ice : IDE-0
3rd Boot Dev ice : CDROM
Floppy Drive Seek : Disabled
As you can see there are selections for drives too.
Do you know the history of this motherboard. Possible you are setting to boot to a network?
The first screen in the BIOS should be the drive setup screen. Are the drives being configured on that screen? There may be an option on that screen to auto detect the drives. If so, click on it.