At Computex 2022, AMD reaffirmed that its AM4 motherboard platform wasn't going anywhere and will continue to serve the PC gaming segment for the foreseeable future and it looks like the company might be considering launching a variation of Zen 4 for it.
AMD Allegedly Considering Ryzen 'Zen 4' Launch With DDR4 Support on Existing AM4 Motherboards
The rumor comes from Greymon55 who has stated that according to an AMD CPU reseller, the red team might be planning to bring Ryzen CPUs based on the Zen 4 core architecture on the AM4 chip platform. The leaker isn't sure if these plans would bear fruit but it would be an interesting decision nonetheless.
According to an AMD CPU reseller, AMD plans to have AM4 DDR4 compatible ZEN4 products.but it's just a plan, not sure if it will be available.
— Greymon55 (@greymon55) June 17, 2022
All things considered, AMD has already announced that Zen 4 CPUs, either Ryzen or EPYC, will only feature support for DDR5 memory so this means that there's no DDR4 IMC on the Zen 4 core. If the red team was to bring Zen 4 on the existing AM4 motherboards, then it would have to make special variants of the chip that house the necessary DDR4 IMC as AM4 is an all-DDR4 platform.
Additional information is shared by TechPowerUp who states that the new Ryzen CPUs for the AM4 motherboards will feature Zen 4 chiplets and may possibly be paired with the existing cIOD (IO die) which supports PCIe Gen 4.0 and DDR4. With the likelihood that AMD's Ryzen 7000 'Zen 4' lineup is probably going to enter the high-end segment first, AMD would want some sort of action in the low end and mainstream segment and that's definitely not what AM5 with DDR5 will be offering at the start of its journey.
In an interview, AMD's Robert Hallock confirmed that AM4 and AM5 will co-exist and there might be new CPUs for the existing platforms:
"AM4 + AM5 co-exist, still markets adopting AM4, from a global point of view, AM4 has alot of life. There might be new CPUs for AM4, but nothing specifically is planned now."
AMD will find itself in a very tough spot against Intel's Raptor Lake which will not only feature full support on the existing 600-series motherboards but also come with both DDR5 & DDR4 support. To tackle Alder Lake, AMD quickly launched a slew of mainstream Ryzen 5000 parts & the top-end 5800X3D CPU. It will have to do the same to keep Intel's mainstream Raptor Lake CPUs at bay and this time, the only possible solution would either end up being more X3D parts on the existing Zen 3 core architecture or a version of Zen 4 with DDR4 compatibility.
With that said, the Zen 4 Ryzen CPUs for AM4 socket won't be targetting the high-end market and we can expect up to 8 cores and 16 threads but that's if AMD actually goes on with the plan. So for now, this is just a rumor but it'll be interesting to see what AMD cooks up for its AM4 user base who might want to hold off the Zen 4 purchase for a generation or two.