hunterz7890 :
is a 750w bronze power supply enough for a i5 6600k and crossfire RX 480?
Depends on the power supply some are overrated junk... And can put out nothing close to the advertised watts.
With power supply questions always list the one your going to use.
Xfire RX 480's is not something I would really consider a good choice. For the games that it scales decent you would be OK but in general for overall performance you would be better off buying a single card. I would look at a GTX 1070 or GTX 980ti it should be in the same or lower price range as 2X 480's. Whatever is in stock and the best price.