Yes, shit, sorry, I just realized how confusing my last post could be.
The point of DirectStorage is that you can transfer data in compressed form, then the CPU or GPU will decompress it. This means you can effectively exceed the bandwidth ceiling of the protocol if it was shuttling the data in uncompressed form. These are those limits:
- NVMe PCIe 4.0x4 (SSD) ---> 7.9 GB/s ceiling bandwidth
- NVMe PCIe 3.0x4 (SSD) ---> 3.9 GB/s ceiling bandwidth
- SATA III (HDD/SSD)----------> 0.6 GB/s ceiling bandwidth
If a game uses DirectStorage, yes, your 7900 XTX can effectively achieve a 12.6 GB/s exchange rate on your PCIe 3.0x4 SSD. As you can see, that's over three times the peak possible on that protocol (this is assuming your SSD actually achieves read/write times close to that, and most are under by quite a ways, only the best 3.0x4 SSDs come close).
And yes, I don't see any reason why a game that was built from the ground up to support DirectStorage on the Xbox wouldn't be capable on PC. This will become a standard.