I was going to say "my current desktop has 4 CD-capable bays", but I checked and it's actually only 3 bays followed by unused space (and then 2.5" and 3.5" bays

I was going to say "my current desktop has 4 CD-capable bays", but I checked and it's actually only 3 bays followed by unused space (and then 2.5" and 3.5" bays below that).