I have since many years AMD video cards in my HTPC. Till last week I used an RX580 (Sapphire 8Gb Pulse) and it worked properly. By downscaling 4K and HDR content to FullHD and SDR the card went very loud, it was streched to the limits, but beside of the very noisy cooling no problem at all. I made a change to Powercolor RX 5700 XT Red Devil to give more muscle and have silence in my home teather. Now I have silence but the card is not working at all. With the same set up (no change in software nor in hardware) after 3 to 8 minutes the palying of 4K, HDR videos will stop.
I tried old driver (19.8.1, 19.10.1) amd the newest one, no change, the problem is there.