Hah,
That's exactly my daily driver. Except instead of 2 vega's, I have a vega and 1080ti.

One video card is for my linux host, the 1080ti is idle unless i spin up either my windows virtual machine for gaming, or the mac VM, for random graphics work. This a beast of a set up, for every compute task. Even have my VR set up in a VM.

The iommu groups are really nice on this mobo too.