There's a lot of possible reasons for Code 43. AMD drivers needing a patch applied is one of them. Although it seems like his rig was working fine before the reboot, so the drivers should be already patched. Looks more like some sort of hardware problem.
Code 43 is exactly the problem with the modified driver. Solutions to problems 2. I know because I faced such a problem. The first method is to install the patch. The second way is to install the latest modification to the driver. This error was corrected and now my GPU is working without installing the patch.