The max mem overclock I can get on 2x Vega56 is 930Mhz and 890Mhz @ 900mV.
They are giving me 1940 and 1860 H/s respectively.
Used powertables in registry and blockchain driver. Everything adjusted through OverdriveNTool without using WatMan.
Any hints on how to get more overclock?
Try flashing your card with the Vega 64 BIOS and re-applying the registry mod (use the 1100 HBM to start, to see if it's stable).