This is a rather complex and puzzling situation that I have put myself in. I recently (Saturday, April 27th, 2020) rebuilt my fiance's computer. I had given her an RX 480 8GB last year and replaced it with an RX 590. I took the RX 480 8GB and put it in my Threadripper build that already has a RX 5600 XT in it. The goal of doing this is to use the RX 480 for compute and the RX 5600 XT for gaming and movies. Also, I thought that the 5600 XT did not support CrossFire? Odd.
I have researched and researched, edited the registry, searched my BIOS (X399 Taichi by ASRock), swapped the graphics cards and even disabled the 480 in device manager. I have disabled CrossFire in the registry as well as ULPS. I just now uninstalled the 480 and reinstalled the drivers while typing this.
The concern here is I believe the computer is crossfiring these cards, and I do not want it to. At all. In the image attached to this post shows that the 480 8GB is utilizing only 6GBs VRAM and the 5600 XT is right with the 6GBs VRAM. When I launch select games (Fallout 76, DOOM: Eternal, Titanfall 2, Battlefield V, and COD: Modern Warfare), I get insane amounts of stuttering to the point that they are virtually unplayable.
Is there anything that I can do here? I want to have both cards in the system and utilize each for different purposes. I do NOT want to crossfire them in any way, but I want to be able to play my games with the 5600 XT and use the 480 for compute.