AMD says there are no technical reasons for not having an X3D processor with 3D V-Cache on both CCDs, but we probably won't see such a dual-stacked chip anyway

Alongside sparse RDNA 4 graphics card details and somewhat denser mobile chip announcements, AMD also announced the Ryzen 9 9950X3D and 9900X3D this CES 2025. Much like their 7000-series counterparts, however, and despite each CPU having two Core Complex Dies (CCDs) full of CPU cores, only one of the two CCDs has 3D V-Cache stacked underneath or on top (underneath for 9000X3D chips and on top for 7000X3D ones).

This, however, doesn't seem to be due to any technical limitations, but just because it's not worth it.