I know tradtionally 4 way has been the maximum for crossfire. With Ryzen having a dedicated 16 pcie gen 3 lanes it should be possible to have 4 cards at 4x according to old standards. Also why in the world do all the MATX motherboards including the one X370 board by Biostar only have a single pcie lane thats Gen 3? The second one is always Gen 2 and runs at x4 speed. I initially thought it was the chipset but the same goes for the BIOSTar GT3 board. I am an lover of MATX and i have an MATX case and im massively disappointed in the MATX motherboards i've been seeing. Almost no X370 MATX boards and absolutely no boards with a second slot operating at Gen 3 or even 8x. I'm really big on powerful yet very small setups. I'd love to do a dual gpu crossfire set up in my Corsair Air 240 but with the way things look even if Vega does make a Dual GPU card (hopefully better than the pro duo) i wouldn't be able to use it to my liking anyway.