Fwiw, I think Apple stopped putting this direct soundcard/cdrom link in its macs a few years ago now.Just to be clear, my actual recommendation was that it should use the old system by default. This is because normal computers are expected to be installed correctly, with the cable connected from CD drive to your sound card (as is the case for any laptop, all machines you buy in a store, and only seems to not be the case for some random guy on bugzilla that probably installed his machine himself from parts and is now too lazy to connect the smallcable).
Christophe