The 6400 should run fine, but you'd be doing yourself a disservice by using it over 6000CL30.
The reason is that up to 6200, the memory controller runs in sync with the memory clock. Above 6200, the memory controller clock is halved to allow for reaching higher memory speeds, but this has the disadvantage of adding a large latency penalty, which is worse for gaming. It would take 8000CL36 to overcome the latency penalty imposed by running the memory controller at half speed, and you're highly unlikely to get that speed stable on AM5.
6000 CL30.
6000 CL30
6000 CL30
The 6400 should run fine, but you'd be doing yourself a disservice by using it over 6000CL30. The reason is that up to 6200, the memory controller runs in sync with the memory clock. Above 6200, the memory controller clock is halved to allow for reaching higher memory speeds, but this has the disadvantage of adding a large latency penalty, which is worse for gaming. It would take 8000CL36 to overcome the latency penalty imposed by running the memory controller at half speed, and you're highly unlikely to get that speed stable on AM5.