X87 chipsets have 16 pci lanes. Those mobos "can" run 3 way sli, it would just be 8x, 4x, 4x (adds up to 16 lanes). which less than ideal. You want at least 8x per lane, which can only be accomplished with a plx chip, which are very expensive. Think around $400 mobos (Maximus Extreme, MSI...