Annoyingly, I seem to have managed to successfully broken my 3dmark install as I can no longer get validated results after it locked up on me. I've reinstalled it and I keep getting an Unknown error.; (problemId:78227032) preventing the result from getting validated. I've tried uninstalling and reinstalling 3dmark to no avail.
I've comfortably got the Vega 56 to consistently get 6 runs all above 7900 GFX score at 1722/1185 but the 1920x produces hugely variable cpu scores from 8600 up to 9200 which is super annoying.
hah well done beating me. Ive had issues before with 3dmark doing this, the system info program it uses caused it. I wonder if that is left behind when you uninstall 3dmark?
Also, have you got the modified bios on your Vega to get those memory clocks? When i reflashed my card to get those clocks, my card now shows as a Vega64 (not with extra cores enabled though).