I have been thinking of a Vega 64 however, I am not sure if I will get any better performance from it over my R9 390 GPU. The prices are scary so I have been holding out till Vulkan support is implemented to decide. Right now, despite the occational frame drops or freezing for a second or so when the fans speed up, I seem to be getting quite smooth playable frame rates at 4k and very high settings (according to the graphics settings) on my single R9 390 (8GB VRAM) and Crucial MX500 SSD. Added to this I am playing, in a Windows 10 VM using GPU passthrough on my main Linux box with i7-4790K (I only use Linux). I am also playing on a 4k TV so refresh rate is only 30hz so probably limited to a max 30FPS. Turning off V-sync results in screen tiring. Alpha 3.0 was also not playable until I got the SSD. So guess maybe I am hoping Vulkan support helps with the frame rate drops and 1sec or so freezing. I am looking at AMD because NVidia cards don't play well in VMs plus AMD cards generally have more VRAM which I heard is more of a thing on in Windows that in Linux.