I haven't looked into deeply but I've heard stories from others with Ryzen boxes that ECC features of the RAM are turned off with Ryzen CPUs installed. Supposedly you can see this in Linux w/dmidecode or other tools. I'd appreciate good links if anybody has them.
Ryzen APUs (i.e., Socket AM4 CPUs with with integrated AMD graphics) do _not_ support ECC UDIMM, _unless_ they carry a "Pro" in their name.
Ryzen CPUs without an iGPU _will_ support ECC UDIMM, _unless_ the mainboard specs specifically tell you that it won't support ECC, or simply omit mentioning ECC UDIMM at all.
Fwiw, I've enjoyed proper ECC on an ASRock Fatal1ty B450 Gaming-ITX/ac with a Ryzen 5 3600 for more than two years now (using GNU/Linux; I am not sure how Windows would fare).
Ryzen CPUs without an iGPU _will_ support ECC UDIMM, _unless_ the mainboard specs specifically tell you that it won't support ECC, or simply omit mentioning ECC UDIMM at all.
Fwiw, I've enjoyed proper ECC on an ASRock Fatal1ty B450 Gaming-ITX/ac with a Ryzen 5 3600 for more than two years now (using GNU/Linux; I am not sure how Windows would fare).