At 56 BIOS (Can't find Hynix 64 BIOS to flash on to try yet), I am able to actually run the mem overclock at 950, it actually won't crash but there is no accepted results, so I find the maximum mem overclock without throwing invalid shares at 890 Mhz.

It's taking 900 mV using overdriveNTool, on hwInfo it's drawing 0.881V just like my previous ref vega56. (Still unsure if this is the core clock power draw or mem clock power draw) This is with registry edit so the undervolt works, compared to ref vega 56, my on the wall power draw has been reduced by about 30 Watt. I imagine the power draw should be the same as ref, the difference is likely due to me running ref vega 56 at 64 BIOS (higher mem/core clock power draw @ 1.35V).

For reference,
before: r7 1700 + rx480 8gb + ref vega56 (64 BIOS) -> ~ 400W
now    : r7 1700 + rx480 8gb + strix vega56 -> ~ 370W