AMD plans to release the beta BIOS for the B450/X470 boards supporting the Ryzen 5000 CPUs in January, but we’re already seeing multiple sources leak the same well ahead of the scheduled time-frame. A while back, Zen 3 support was unofficially brought to even the paltry A320 ASRock boards, courtesy of a Chiphell forum member. Now, the Zen3 beta BIOS for the B450 boards has also been shared on Reddit.
The BIOS contained in the above link includes an update to the AGESA version 126.96.36.199 which introduces support for the Ryzen 5000 CPUs. However, keep in mind that you’ll likely lose support for the Zen and Zen+ based processors upon updating to this version.
These BIOSes are first variant of the BETA versions intended for the 400 series board and won’t be officially released by ASRock. As such, there may be some bugs or compatibility issues with this version. Flash at your own risk.