The majority, if not all, modern Intel and AMD motherboards have adopted the modern UEFI (Unified Extensible Firmware Interface) firmware. Nevertheless, they are still equipped with a Compatibility Support Module (CSM), whose job is to emulate a conventional BIOS (Basic Input/Output System) environment for certain legacy operating systems and non-UEFI hardware. CSM is normally enabled by default on many motherboards to allow users to plug non-UEFI hardware into their systems without having to tweak any setting inside the UEFI.
According to TechPowerUp's research, the Radeon VII's vBIOS doesn't come with UEFI support or a GOP (Graphics Output Protocol) driver for the matter. The GOP driver is important as it's the component that's responsible for display duties during the pre-boot process. For the Radeon VII work, the user must have CSM enabled, which means losing Microsoft's Secure Boot feature and potentially increasing boot times during cold boot. From a performance perspective, the Radeon VII should perform the same whether it's using a non-UEFI BIOS or UEFI GOP BIOS.
It's highly possible that some of AMD's early production Radeon VII units slipped by the chipmaker's quality assurance department and made their way to AMD's add-in-board (AIB) partners. We suspect that AMD has probably provided its partners with an updated UEFI GOP BIOS. ASRock, for example, has already uploaded the new Radeon VII BIOS on its website. It was possible to find traces of UEFI support and the GOP driver in the ASRock BIOS after opening it in a hex editor.
Although the BIOS is labeled for the company's Phantom Gaming X Radeon VII model, it should work on any and every Radeon VII considering that there are no custom models and every brand is practically selling the same reference model in a different box. ASRock's solution is pretty simple and straightforward as the user only has to download the ZIP archive and run the one-click executable with administrator privileges. Once the process has finished, a simple restart is required, and you're good to go.