I don't know if this has been covered, but the 990FX chipset by AMD does allow dual x16 (not dual x8's) cards in SLI/crossfirex. Of course you would have to use an AMD processor to be able to get this. You can do 4 Radeons at x8 each in the board I have. Lotsa haters of AMD out here, though, but I have MSI 990FXA-GD80. Aside from a bit limited on OC flexibility (i got my FX-8120 to 4.2 from 3.1, but is stable at about 3.9, I find) it is a very capable board with lotsa connectivity.