We tried several setups while testing the 8N SLI Quad Royal. What we plugged in were two Gigabyte 3D1 GeForce 6600 GT graphics cards, plus two 7800 GT models from Asus. With the SLI paddle switch card set to SLI mode, the system would recognize one of the 3D1 cards as a single GPU model only (see the first Device Manager screenshot) and would log in both 7800 GT cards normally. After setting the paddle to single mode - assigning the full 16 lanes to the card - we got a total of three 6600 GT devices (one 3D1 running in dual mode, the other in single) plus the two 7800 GTs (see second screenshot below). Of course it was possible to mix three different NVIDIA graphics cards - the system would log these in and allow the use of all display outputs simultaneously.