I changed to cast xmr from xmr stak.
Much more simpler and steady hashrate. Hashrate is definitely higher than xmr stak at the same power useage.
Cast xmr , latest drivers 1750hs for each vega56 @140w at the wall
I'm getting 1850h/s with sapphire pulse vega56 (hynix) 1456/970@0.875v 140watt according to corsair link
SrbMiner