TechPowerUp published AMD Ryzen 5000 Processors Allegedly Work With 300 Series Motherboards
A quote from the article:
When AMD initially announced that their next-generation Ryzen processors would only support 500 series motherboards they faced significant backlash and were forced to include 400 series motherboard support. The reason AMD cited at the time was the limitations in some flash chips not containing enough space to store the information for all processors, several motherboard manufacturers encountered this issue with Ryzen 3000 bios updates where they needed to reduce graphical elements in their BIOS.AMD Ryzen 5000 Processors Allegedly Work With 300 Series Motherboards