I set all of my RTL's to 60 (after RTL/IOL Training enabled) and IOLs are at 4.
It is still happening sometimes at coold boot or when doing reboot from Windows 10, 1 out of 10 cases now with boot voltages.
I can live with that. Code 3A, 23 or 55, then 1-2 reboots and it is stable. Feels more like is a BIOS issue, since my i9-9900KS IMC can run the ram at 4266mhz with only 1.6v on vccsa and vccio... and everything is stable. Maybe bad memory trainings? I will also try to dowgrade the BIOS, running 1802 now. Hopefully soon the Maximus XI Extreme will have resizable BAR support and also those issues will be mitigated.