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
Thanks again.
So it should be safe to assume that ref and aftermarket are about the same, except for the slower memory. Did you use the same registry tools (and .reg files) that you used in the ref card (I guess they're the same)?
With only 1 card I can never be certain if the memory manufacturer is the fault for overclocking tolerance, or it might be due to how the BIOS is programmed (I really doubt that but if it can be fixed via software it will be awesome), but your assumption is more or less correct. Aftermarket is essentially changes on the heatsink + cooler design, and also possibly some BIOS tweaks from each brand themselves.
The registry file for my ASUS strix doesn't come with softPTTTable, so I merely apply the one I had for previous ref 56 onto it and it will be effective after a disable/enable or full pc reboot. I don't recall if there's any major difference between ref 56 core clock and mem clock out of the box vs Asus Strix, so the registry application is meant for undervolting and power draw reduction (adjusting core clock p2 to p5).