Wenn it comes to the X470 line of boards the Asus Crosshair VII Hero has the best vrm out there.
10+2 phase design with by IR3555M 60A powerstages.
And also the best bios for overclocking imo, for what its worth on Ryzen in general…
The Asrock X470 Taich still has the same vrm as its X370 preducessor.
Its still a decent vrm with 12+4 phase design with 25A / 40A max CSD78350 Ti Nexfets.
But Asrock’s bios still has some points that could be improved on.
The only thing i have to mention about the build in the OP,
is that 850W for a single RTX2080 shouldnt be needed.
Unless you plan to do an sli setup.
But then i’m not fully sure that AMD Ryzen would be the best choice really.
Depending on the main workload you want to use this machine for,
which i’m assuming is gaming. Unless your gaming goals are gaming at 4K ultra with a single RTX2080. Because then you will be gpu bound most of the scenario’s.
But gaming on a RTX2080 sli setup, then intel is probablly where you want to be in terms of cpu horse power.