When I was mining ETH with my R9 290 cards (all Sapphire Reference design, with a bios from TheStilt), they were generally pushing just a hair under 30 Mh/s running 1100 core / 1250 memory as I recall - under LINUX so the only undervolt was out of the modded BIOS.
No idea what the "aux" setting you reference is, and TDP at stock.
If I change the Core Voltage in MSI AB, there is this small arrow that brings up the new window (Triple OV or something). There are some more voltages you can play around with and one of them is this AUX.No idea what the "aux" setting you reference is, and TDP at stock.
Pic from Google:
http://s011.radikal.ru/i317/1505/bc/0c7307083809.png
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