Hello, after hours and hours and searching the forum for configurations to do thousands of tests. The only thing I can get out of my Vega 56 from Gygabyte with Hynix HBM2 is 47.5MH / s. Even so, sometime I get a Dead GPU back and the Rig reboots.
Try 1075 core and 950 mem to start, or 1050 core and 950 mem. If it still crashes, maybe try flashing a different bios. All of my cards are flashed with the same Vega 56 bios (of the same version) from Techpowerup. For instance, I backed up all of my original bios files, downloaded a Powercolor Red Dragon Vega 56 bios from Techpowerup, and used that to flash all of my Red Dragon cards. And some of the bios versions seem to work better than others, so it may take some experimentation to get one that works with your card.
On my MSI Vega 64 card, I couldn’t get an MSI Vega 64 bios to work, so I ended up flashing it with a Powercolor Red Devil Vega 64 bios. Now it works great.
So the first thing I’d do is mess with the core and mem settings. If that doesn’t work, try flashing it with different bios files.