In a seemingly massive quality control error on the part of AMD, AMD Radeon VII graphics buyers have reported that their cards do not support UEFI, so the motherboard, by installing on their machines, activates the CSM (Compatibility Support Module), a component of the UEFI firmware necessary to boot the system when UEFI-compliant hardware is present.
The TechPowerUp website attempted to confirm the allegations and use a hex editor with a Radeon VII card, and what they found was surprising.
The AMD Radeon VII cards have no UEFI support at all, even the Graphic Output Protocol (GOP) driver is missing, so you can perform basic actions on the card before starting the system.
Without UEFI support for graphics cards, Windows 10 cannot guarantee secure start-up. Since secure start-up is a prerequisite for hardware that bears the Windows 10 compatibility certification logo, AMD is unable to claim that these cards are compatible with Windows 10 at this time, at least not until an update.
ASRock is the first AMD partner to release a BIOS update to fix the problem. And although this update was developed for Radeon VII phantom cards, it works on any Radeon VII card, so flashing on the ASRock card or any other AMD Radeon VII card is not a problem.
If you look at the ASRock update file, you will see that it already supports UEFI, including the GOP micro-controller. It is likely that all AMD Radeon VII cards on the market do not have UEFI support, but it will not be long before the BIOS of all AMD partners is updated.