"Only the X570 and B550 motherboards will support Zen3. The news comes as a blow to currently B470 owners because those motherboards will not support Zen 3, AMD confirmed today during pre-Ryzen 3 launch briefing.
An important note, the slide posted by AMD clarifies that the Ryzen 3000G series (with integrated Radeon Vega graphics) will not be compatible with B550 motherboards."
AMD announces B550 chipset with Zen3 support | VideoCardz.com https://videocardz.com/86882/amd-announces-b550-chipset-with-zen3-support
Zen3がX470をサポートしないのは理解する (良いとは言ってない) として、B550がZen+ APUをサポートしないのはどうなのよ、という感じ。3000番台Ryzen向けじゃねえのか、500番台チップセットは
Zen2と300番台チップセットの時点でもそういう問題があったのか。もう、UEFIの一部をSSDやHDDに載せて、2段ブートとかすればいいんじゃね???
BIOS ROMサイズの制限AMDのZen2下位互換性の約束がほぼ崩れる https://g-pc.info/archives/10883/
BIOS Flash ROMの容量制限だけなら、Zen3 ReadyのB450マザーボードが出てきそう
"AMD has highlighted the main reason as to why they don't plan on adding support for Zen 3 Ryzen CPUs on pre-500-series chipsets to be the flash memory limitation. "
AMD Ryzen 4000 'Zen 3' CPUs Compatible With X570 & B550 Chipset https://wccftech.com/amd-confirms-ryzen-4000-zen-3-cpu-compatibility-x570-b550-chipset-motherboards/