As expected, any supported CPU must be listed on main CPU support list.
Asus B350 no Renoir support, or same story with one random MSI B350 motherboard example.
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Asus is starting to roll out bios updates for their B350 and X370 boards ahead of time using Agesa 1.2.0.6b
PRIME B350-PLUS|Placa base|ASUS España
La serie ASUS Prime está diseñada para aprovechar todo el rendimiento potencial de los procesadores AMD e Intel. Equipadas con un potente diseño de alimentación, soluciones de refrigeración completas y opciones de ajuste inteligentes, las placas base de la serie Prime incluyen ajustes de...
www.asus.com
They havent updated the cpu support list yet, 1.2.0.6b should fully support Renoir and Vermeer, but not Cezanne.