I have 2 asus r9-280X dc2 t 3gc5, latest CCC 14.4, 1200 watt psu. Installed in slot 1 and 5 of a chvf-z. GPU-Z shows both cards, 1 at x16 and 1 at x8, shows Crossfire enabled. I can enable or disable crossfire with CCC and operation appears normal...