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AMD's next-gen Zen 3 CPUs will work in 400-series motherboards after all

(Image credit: MSI)

AMD likes to flex the longevity of its AM4 socket from time to time, though it sometimes comes with caveats. The latest example of this came less than two weeks ago, when AMD confirmed its next-generation Zen 3 CPUs will slot into socket AM4 motherboards, but will only be compatible with 500 series mobos (X570 and B550). That meant your swanky X470 motherboard will not support the next round of AMD processors. Or at least that was the case. Now AMD is saying it has "decided to change course" with regards to supporting Zen 3 on X470 and B450 motherboards.

How did this come about? Well, AMD chalked up its initial decision to leave X470 and B450 (and earlier) motherboards behind because the BIOS chips simply are not fat enough to fit the necessary microcode to support yet another round of processors.

"While we wish could enable full support for every processor on every chipset, the flash memory chips that store BIOS settings and support have capacity limitations. Given these limitations, and the unprecedented longevity of the AM4 socket, there will inevitably be a time and place where a transition to free up space is necessary—the AMD 500 series chipsets are that time," AMD said at the time.

It seemed AMD was looking to avoid a repeat of having to loan out chips to DIY builders who wanted to pair a next-gen CPU with a previous-gen motherboard, as it had done before.

Whether AMD will actually to go that route again remains to be seen, but either way, AMD now says X470 and B450 motherboards will in fact support Zen 3.

"As the team weighed your feedback against the technical challenges we face, we decided to change course. As a result, we will enable an upgrade path for B450 and X470 customers that adds support for next-gen AMD Ryzen processors with the 'Zen 3' architecture," AMD announced today on Reddit.

AMD notes this is a "very fresh" decision with "still many details to iron out," and said more details will be outlined in a blog post closer to Zen 3's launch. In the meantime, AMD provided a bit of preliminary information about how this will work.

To make space within the apparently cramped BIOS, AMD says the optional firmware updates that add support for Zen 3 will "disable support for many existing" Ryzen processors. AMD didn't say which ones, but I suspect first-gen Zen CPUs (Ryzen 1000 series CPUs and Ryzen 2000 series APUs) will get the axe.

The other interesting tidbit is that anyone who decides to flash a beta BIOS to add support for Zen 3 will have to be supremely confident in their decision. Should you change your mind and want to go back to a previous BIOS, you'll be out of luck.

"The select beta BIOSes will enable a one-way upgrade path for AMD Ryzen processors with 'Zen 3', coming later this year. Flashing back to an older BIOS version will not be supported," AMD says.

I can't imagine many people would ever want to downgrade from a Zen 3 to a Zen 2 CPU anyway, though the risk with a one-way upgrade extends beyond the CPU. If a BIOS update somehow breaks functionality or otherwise causes problems (maybe your onboard Wi-Fi starts acting wonky, or not all), too bad.

Risks aside, this a good move by AMD. It's also the end of the road for X470 and B450, a point AMD made in no uncertain terms.

"This is the final pathway AMD can enable for 400 series motherboards to add new CPU support. CPU releases beyond 'Zen 3' will require a newer motherboard," AMD added.

Of course, that could very well be the case for 500 series motherboards as well, assuming AMD finally adopts a new socket for Zen 4.

Paul has been playing PC games and raking his knuckles on computer hardware since the Commodore 64. He does not have any tattoos, but thinks it would be cool to get one that reads LOAD"*",8,1. In his off time, he rides motorcycles and wrestles alligators (only one of those is true).