Futuremark's brand-new VRMark Cyan Room benchmark arrived earlier today and the first set of interesting results is already available. According to AMD's own tests that were conducted using this DirectX 12 benchmarking tool, the RX Vega 64 is 20 percent faster than the GeForce GTX 1080.
https://www.notebookcheck.net/AMD-s-RX-Vega-64-is-20-percent-faster-than-the-GTX-1080-in-DX12.264450.0.html