To save the transistor budget, the Radeon RX 6000 and RX 7000 video cards received up to 128 and 96 MB of Infinity Cache. The bottom line is that a rather modest 256-bit bus for top video cards, together with Infinity Cache, provides a memory bandwidth at least comparable to a conventional 512-bit bus.
The benefits of Infinity Cache on the example of Navi 21 (RX 6000)
Engineer Tom Wassick took a look at the Navi 31 GPU used in the Radeon RX 7900 XT and 7900 XTX and found something interesting. MCD chips containing memory controllers and Infinity Cache have unused TSV connections. Similar AMD uses in the Ryzen 5000X3D and Ryzen 7000X3D processors with an additional third-level cache.
Presumably, in the Navi 31 scheme, AMD pre-embedded the ability to increase the cache memory. It is possible that in the future the Radeon RX 7000X3D or Radeon RX 7950 will be released, featuring an increased cache size.
