"If your computer is relatively new you don't need to connect the data cable. The sound is carried through the DATA cable
Actually, that's determined by how old the optical drive is. E.g. ! have CD-Rom drives that were made in 1999 and earlier and they are able to send all audio to the mboard through the data cable on mboards that are as old as 1995.
If you're not getting regular CD audio when you have no audio is cable connected to the CD drive, if the CD drive is not ancient, you need to change a setting in XP so everything goes through the data cable.
Device Manager - DVD/CD-ROM drives - RIGHT click on the name of the drive - Properties tab
click on the box beside Enable digital CD audio... to insert a checkmark if there isn't one there.
If that's not there or if it is but it's greyed out, your CD drive is ancient and doesn't support that, or, your mboard is so ancient that it doesn't support that. .
In that case, some sound cards (that you install in a ISA or PCI slot) have the pins you're looking for.