The reference boards for the rx480 what I'm expecting from them, is that they are the best perf/watt cards you will get compared to the AIB overclocked ones. I think AMD took the best range for frequency, voltage, heat production, and used that for their reference board, and are letting the AIB's bin them as they wish.
and it gives them large quantities to push out too. AIBs can stack up on binned chips and do as the please. Win win, more profit for them.