In a surprising yet pleasant twist, AMD has extended Ryzen 4000/Zen 3 support to B450 and X470 Motherboards. This comes with a few caveats though which will be outlined below.

There was a huge backlash from fans when AMD dropped support for 400 series motherboards. And rightly so, as it would mean a dead end for upgradability for those who bought them. This also comes after ODMs like MSI have already come out saying their Mobos especially their ‘Max’ line-up will support future AM4 based CPUs. So it wasn’t only AMD who was under fire.

This problem stemmed from the fact that the BIOS has a limited ROM capacity of 16MB. So they had to come up with a solution to get around this restriction.
The Caveats of Supporting Zen 3
Now coming to the caveats, the upgrade path will be uni-directional meaning you can’t downgrade the BIOS back to use the Zen 2 and earlier CPUs. This is owing to the fact of limited BIOS ROM available as mentioned earlier. This will essentially cause the support of Zen 2 and older CPUs to be dropped.
The ‘beta’ BIOS will be developed in collaboration with the motherboard partners. And its rollout might not coincide with the launch of Zen 3 later this year.

To avoid problems similar to the Zen 2 and B350 Motherboards. AMD will allow the download of the beta BIOS to only verified ‘Zen 3’ customers. This is to avoid laymen who have a Zen 2 or older CPU to accidentally upgrade their BIOS and get locked out.
Finally, AMD hammers the point that this will be the final upgrade pathway and subsequent CPUs such as Zen 4 will not be supported. While they do offer the ability to be able to run Zen 3 CPUs on the B450/X470. AMD recommends customers to use a 500 series motherboards to get the best performance and exclusive features.
Overall this is a great gesture from AMD, listening to fan feedback and acting on it. This will make sure they don’t lose all their hard earned goodwill over the past few years.