I've actually got 4 cards sitting on the board, 4th disabled. During boot it'll end up with 1/2/4 on even though 4 is disabled.
Once on desktop all 3 are recognised but when sli is enabled only the 1st two end up in sli. All 3 show up if i render test the 1st two, only the 3rd when testing the 3rd. 3rd also running at 1.1, 1&2 3.0.
I've also pulled the 4th card and it's the same in desktop, only difference is the lane lights are now correct, i.e, 1/2/3.