I've changed a few things from stock settings. Brought down VSOC to 1.2V and increased VDD to 1.45V from 1.35V stock. These tunings are stable and passed TM5 Anta777 Extreme for over 6 hours as well.
My 9800x3d is running at a -35 CO and I can't get it to run stable above 5.4 GHz manually either and PBO is doing that for me all the time, so I've left things on auto-pilot on this one.
My stock timings were 30-40-40-96 which I've dialed down to 28-36-36-48. 2133 MHz on the FCLK wasn't stable as far as I can remember so the max I could push my RAM would be 6200 MHz at FCLK 2066 MHz.
These are a mix of buildzoid's timings and some custom tweaks I've done after 30+ hours of testing. Lmk if I can make things better for both CPU and RAM if possible.