Reinstalling the graphics driver doesn't always make a difference as there are always files left over scattered throughout the system. I would check in the driver itself if there is a high-performance option there that got checked somehow. I haven't had an AMD card in quite some time, but there should be something of that sort. Another thing to check is if you accidentally pressed the dual-BIOS button of that card. It has a legacy and UEFI mode. Could be something with that.
