Environment
Ryzen 9 7900X, B650 motherboard and a 2x32 GB DDR5-6000 kit.
What happens
Enabling the memory profile causes repeated training cycles and a fallback to 4800 MT/s.
What I have tried
Reseated both modules and tested each stick individually with no errors.
I would appreciate advice on how to identify the root cause without risking existing data or configuration.
Verified community troubleshooting
The important clue is that the problem only appears under the conditions you described.
Likely cause: The current BIOS memory training parameters are unstable with dual-rank DIMMs.
What I would try: Update the BIOS, load optimized defaults, enable the profile and reduce memory speed one step while keeping the rated voltage.
Avoid applying several fixes at once, otherwise it will be difficult to know which one mattered.
I can reproduce it consistently, so I should be able to confirm whether this solves the root cause.