It depends on your card (memory, quality of cooling, including vrm and memory cooling, power supply system).
In fact old samsung based rx480 and rx470 cards are very good (not mention power color red dragon crap without memory cooling)
Old hynix and old micron rx480 and rx470 cards are not so good as modern rx580 and rx570 cards with the same memory manufacturer.
Moreover, old rx480 seems can handle only 1100-1140mhz gpu clock @ 900mV but new rx580 can handle 1200-1240mhz with the same voltage. New revision boosted stable gpu clocks by ~100mhz