I did some digging and I missed a few things...
No HDMI audio at this time with AMDGPU (i.e. GCN 1.2 cards, R9 285/380 and newer), but using the older Radeon Kernel driver (GCN 1.1 and older, my R7 370X can use either/or) can use HDMI audio....
As of Kernel 4.12, no video support (missing something to actually display), and no HDMI audio.
But other workloads that the GPU can perform do work... so I would have to wait a bit until the respective code is completed and "mainlined".
However, a few days ago, I checked the local prices again...
and the CPU has dropped $150 (now $350) since March when I priced everything...
BUT, 32GB (2x16GB sticks) DDR4 was $130, it's now $320!!!
And video cards have jumped from ~$240-300 for most brands of RX 580X, to $450-550!!!
Because of digital currency "mining". I'm still trying to find out what that is all about...
I still have not been able to find a clear explanation of what it is exactly.
But it has driven the price up substantially. All I can say is that I hope that it becomes MUCH less popular soon. So prices will get back to "normal".
But at this rate, it's only $50 difference between and RX 580X and a Vega 64.
So might as well wait...
Edit: I almost forgot the point of the prices, the total cost would be up from just under $1,500, to ~1,700. All due to the higher RAM and Video card prices...
Barracuda