Let's start here.
Do you have both power plugs on the GPU connected?
Did you use DDU to clean out those nasty old NVidia drivers? An essential step.
If you didn't, then do it and reinstall your AMD driver when done.
ASUS TUF X570 wifi, AMD Ryzen 5 5600G, ASRock 6700XT Challenger, Antec Truepower new 700w. 32GB