Infinity fabric (FCLK) tops out on AM4 CPUs at around 1900, if you're really really lucky you may get 2000 which would mean RAM at 4000 may work but those chips are few and far between. The infinty fabric runs 1:1 with RAM speed, if you don't run it 1:1 (out of sync) you lose performance.
Sweet spot is 3733 RAM and 1866 FCLK, most chips will do this. With a bit of tuning then 3800 and 1900 is mostly doable.
My advice is to buy a 3200 C14 b-die kit and overclock to 3800, or get a Ballistix kit of 3600 C16 and again OC to 3800. There's plenty of copy/paste settings round the internet for those kits.