Had same issue with old RX480. thought it's dead GPU, bought this one a mount ago.
Pluged it in, removed old driver with DDU and instaled a new one.
Issue from the picture continued to happenm, thought it was PCIe slot is faulty.
Changed MB from gigabyte b450 to Aorus b550.
issue stayed, today i changed PSU and all the cables, changed power socket i was using. And still the same issue.....
