I just built a new system for mining.  Asrock Z170 pro4, g4400, 8gb ddr4 -- looks like i made a mistake.  seems others are having problems with Z170 chipset too?  It has 2 16x slots 3 1x slots, i have 1x usb powered risers -- but system wont boot or run stable. screen corrupts display even in bios, but if i unhook the 1x risers it works fine again. My AMD Fm2+ rigs are all working fine with non usb risers 4 cards going 24x7  I was looking forward to running 5 or 6 cards per motherboard when 480s ship.