A while back, rumors had started popping up that AMD might repurpose its Zen 4 processors for the existing AM4 socket to satisfy the needs of the budget PC audience. However, unsurprisingly, that seems to have been a hoax. According to ProHardver, board partners have no information on any such chips, and Zen 4 is almost certainly going to be restricted to the newer AM5 socket.
There’s a design limitation preventing AMD from bringing (even if it wanted to) Zen 4 to the existing B450/B550/X570 AM4 motherboards. The AM5 socket has been designed to be compatible with existing AM4 coolers which may not seem like a big deal but it actually is. The 5nm Zen 4 chiplets are designed so that their height allows for the IHS to be compatible with older heatsinks and AIO coolers.
The Zen 4 chiplet won’t actually fit optimally into the AM4 enclosure and making it would require redesigning the chipset itself so as to make its height suitable for the legacy socket. On the bright side, the outlet claims that there’s a dual-chiplet 3D V-Cache-based Zen 3 part with a whopping 128MB of stacked L3 cache (200MB overall) that may be launched later this year.
It’s hard to say whether this is a mere prototype or a retail design but AMD is heavily investing in 3D stacked V-Cache. The Ryzen 7 5800X3D which was launched nearly 2 years after the mainstream Zen 3 family, manages to offer generational gains in gaming workloads, fighting the Intel Core i9-12900K inch for inch.
Multiple rumors already talk of Zen 4 chip leveraging 3D V-Cache with a targeted launch window of Q4 2022, so it won’t be surprising if AMD manages to sneak in yet another AM4 flagship with twice as much cache as the Ryzen 7 5800X3D.