Hi, please be sure to try all Maximus Tweak modes. The suggestion from GSKILL to check the timings may help as you might need to relax the sub timings somewhat. Also try the following
18–18-18-42 at command rate 2
DRAM Voltage 1.4v
Beyond 3800 can be tough on some CPU samples as this is the very top of the spectrum for SKL-X.*
13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090