I have moded asus 470 8gb with micron and it gives me 27.7mgh using 1138/1954 using the latest polaris bios editor to edit the timings , you are good to go! Just remember never to put the card as a first one and attached to a monitor, cause it will freeze the machine when the miner stops and then started again. it will not gtive you memory errors , but it is restarts the machine when miner stops and starts. If you keep it away from a monitor it will hash forever with no problem!
What straps are you using? And are you undervolting the card at all?
Will try yours but I tried using your clock settings and still getting 25MH at most. This is while using the 1600 straps, cvddc at 890, and mvddc at 920.
Gettin 28.9 - 29.4 depending on mem clocks in dual mode with LBC.
Need bios - contact me.
Also check your ASIC quality.
Otherwise - use 1750 straps and abt 2050 mem clock. 0.9V undervolt is fine with these cards.
Also check therm pads.
Those are nice hash rates. Especially for a MICRON memory rx 470. Don't your cards crash?
Mine go black screen whenever i exceed 2000 mem clocks.