Crossfire has not been enabled in the drivers yet and 850W PSU is like a ticking timed bomb with two way crossfire RX Vega or the PSU will turnoff.
was reading people whining andcomplaining on reddit then I seen these pop up but it is reddit take them with a grain of salt and I don't think crossfire or sli ever worked on release but it has been a few years since I tried crossfire or sli.
and