Got myself a Matrox G550 PCIE card, it's the only PCIE X1 card but it fits just in the x1 slot above the 2 x16 slots on my DFI SLi-DR mobo. Installed the drivers and activated the second screen and that's it, dual desktop in SLi mode. Searched high and low on the net for this and I coudn't find anyone who has done this with a Matrox G550 PCIE x1 card.