This card is one helluva GPU to work with. Uber Mix 3.2, 3.1 or any other version causes freezing and grief. OC'ing greater than 2050 causes the same amount of frustrations as well.
BUT...
I have the same card (6 of them) and do 29.4 eth only.
For dual-mining, 29.3 eth + 580 dcr @.88xx mV pulling 118w GPU-Z.
Not sure if OP has better BIOS (or results) than me but if not, feel free to PM me

With stock Uber-mix 3.1 RX 470 should doing around 30MH/s and RX 480 30-31MH/s. I also have tweaked Uber-mix 3.1 that allows higher clocks and hashrate 31-32MH/s, but not stable on every card, it still need some tweaking.
118W in GPU-Z? None of my cards showing 90W or more in GPU-Z. 118W at wall maybe.