Read about the asrock x79 board which has a pci-e 3.0 switch in it (PLX PEX8747). So yeah no reason this couldn't be used in an IB board to give you all the lanes you need, just a question if nvidia refuse to support it, but the article claims that this board at least does support quad sli:

http://www.techpowerup.com/161780/AS...therboard.html