hi,
I have 6 rx 470 nitro+ 8 Gb and all my card can do -96 mv.
For XMR 600 W for 4500 h/s in sgminer-gm so your result are not so great.
100h/card more than you isint great? My cards do -125mV, and its a really easy thing to mod in the bios, OP has stock voltage, surely you must understand what that entails. Editing the timings by hand, not that easy.
It's better to just ignore those posts mate

There are always haters out there

You know what you can do, i know, that's more than enough.