Here's my attempt at a RAM fan setup for the 5866Mhz CL21 5.1Ghz CPU profile, but it's most likely unnecessary. Depends on what temps you're comfortable with.
For me, I don't think I could run a RAM kit all day long at over 38C-40C, even though it's absolutely within spec.
A simple Noctua NF-S12B redux-700 fan which barely pushes any air at all, even at stock 700rpm. Did achieve ok results - the 5333Mhz Gskill kit at 5866Mhz CL21 maintains a steady 34C with the RAM fan offering only a gentle yet inaudible airflow.
5333Mhz and 5600Mhz ram kit profiles - thermals remain in the mid 30Cs with no fan at all. 🙂
Z790 Epiphenomenal Raptor Bench
ROG Z790 Apex / Intel 13900KS SP111 P121 E93 MC83
Gskill 8000 kit - TM5 stable at 8200MT/s 38 48 48 121 VDD and VDDQ 1.5v
WD_Black SN850X 1TB 7300MB/s Reads 6300MB/s Writes
LG 32in 4K IPS 32UP83A-W