New Sapphire rx 570, fresh build as below:
ASRock B450 Steel Legend
AMD Ryzen 5 3600. (No internal GPU)
Western Digital NVMe M.2 boot disk
On first boot, BIOS booted fine, blue Windows screen w/rotating circle led to ... black. MB still powered on, but rx 570 shut down...won’t finish booting into regular Windows 10
Boots fine into Safe Mode; installing GPU driver in Safe Mode leads to “unsigned certificate” error 99. Deactivated unsigned certificate enforcement in the list after Troubleshoot Advanced restart, but since it won’t boot into regular Windows 10, booting into Safe Mode undoes the deactivation of unsigned cert enforce, so driver still won’t install.
Build boots and operates fine with an Nvidia 1080 installed in the same - main - PCIe slot - after RMA’ing the rx570. Reinstalling the replacement rx570 repeats the above.
I have removed all traces of prior drivers using DDU, still won’t install in Safe Mode and still won’t boot into regular Windows 10. Will run in Safe Mode as long as I want; I’m assuming that means the PS is OK (?).
Any ideas? I’m right at the edge of my knowledge, so I’d really appreciate some much smarter help ;>)