For people trying to run their ram at their rated speed, try setting your fabric clock (FCLK FREQUENCY in BIOS) to 1600 or less (Stock is 1066). I have had good success doing this and I am able to run RAM up to 4733MHz perfectly fine with no WHEA / bus interconnect errors. See attached photo.
Keep in mind, this is considered a BANDAID fix. FCLK should be fully capable of 1900-2100 on Zen 3 (Ryzen 5000 series) without any errors. This just bypasses the issue.
AMD AGESA ComboV2 18.104.22.168 (C), while being the latest revision, is STILL a BETA BIOS. It is the same V2 code AMD released to ALL vendors. The problems are certainly not unique to MSI 5XXX motherboards either. Perusing on the GByte, ASUS, ASROCK, etc. forums V2 22.214.171.124(C) is not performing as well as expected and won't last long on the "BETA BURNER."
Looking on this forum alone, you see the most premium MSI X570 & B550 boards (Ultra, Ace, Godlike, Carbon) all having quite similar BUGs that are causing similar operating headaches (USB failing, GPU failing to post, 36XX+ DRAM not running past 2133, etc.
As much hype as AMD spun rolling out Zen3
, there wasn't as much "refinement" in their V2 AGESA code for Zen3 this time around as there was for V1 AGESA Zen2. I don't think I'm just imagining that, especially since the higher end boards are all reporting very similar BUGs
in the early AGESA implementation.