AMD's Radeon VII makes the GeForce RTX 2080 from NVIDIA look a lot better but it appears the former also suffers from a big QA oversight. TechPowerUp writes the Radeon VII does not have UEFI support. This results in systems booting in CSM (compatibility support module) mode, which is usually used for old, UEFI-unaware hardware.
To verify this claim, we put the stock video BIOS of our Radeon VII sample in a hex editor, and what we found out startled us. The BIOS completely lacks UEFI support, including a GOP (graphics output protocol) driver. A GOP driver is a wafer-thin display driver that runs basic display functions on your GPU during the pre-boot environment. Without UEFI support for the graphics card (i.e. with CSM running), Windows 10 cannot engage Secure Boot. Since UEFI Secure Boot is a requirement for Microsoft Windows 10 Logo certification, we are having doubts whether AMD can really claim "Windows 10 compatible" for Radeon VII, at least until a BIOS update is available.
The issue will be resolve via a BIOS update. At the moment, ASRock already has an update for its Radeon VII Phantom Gaming graphics card, which should work for all Radeon VII cards as these are all reference design cards.