You cannot use an RX 480 with a GTX 1060 except for with newer DirectX 12 titles that support multi graphics. Right now only 1 game Ashes of the Singularity supports it and I would NOT make purchasing decisions based on this feature, as it needs to be implemented in game, so devs may well never use it.
Pairing the 2 cards for older titles does nothing, it doesn't work.