2 way sli is the most any Z170 board can do without a PLX chip to add additional pcie lanes, no ASUS boards are using that except maybe the work station board
except Nvidia specs = 8x pcie minimum, AMD specs 4x pcie minimum, so 2 way sli, maybe 3 way crossfire
well that's incorrect, maybe that was the original plan, maybe not but there isn't one, if you want or need 3 plus GPU's X99 and a 40 pcie lane CPU is the better option
