I'm a novice at the newer stuff but I have added a floppy drive before. I know the ribbon cable was NOT a standard IDE cable. I'm looking at the cable I salvaged last week from this computer. One end looks like the standard cable which goes to the controller. The other end is very different.
I would suggest searching on how to go from a ide controller to a floppy drive first; this would include cabling, etc. I kow this mobo has 1 ide connector (pata not sata); now see if this connector can be used for a floppy drive with the cable you looked for earlier.