homelab

The only AM4 and AM5 motherboards I'm aware of that officially claim to fully support ECC are made by Asrock as their server sub-brand Asrock Rack. They are pricey AF - 500-600 euro for the motherboard alone. As a bonus you get 2x10Gb ethernet + separate ethernet port for remote management, including bios access and a bunch of other goodies.

I used one of those (Asrock Rack X570D4I-2T) for my NAS - it comes with 2 oculink ports, each of which provides 4x SATA.

Unofficially ECC works on many (possibly all) B an X chipset series motherboards as long as you are not using G-series CPU. If you google around you'll find a bunch of unofficial confirmations from users of specific motherboards that it does work.

E.g. Asus PRIME B650M-R + Ryzen 7600 (non-x) is a good start and will cost you 250-300 euro total. LSI 9300 16I will add 16 SATA ports for another 50-60 euro. 200-250 euro for a 2x16GB ecc kit.

What Ethernet speed do you want?

ECC RAM is quite pricey. That could be a stretch.

Random suggestion, but look for a cheap X3D CPU if it’s in the budget, like a 7600X3D or a 5500/5600 X3D.

They’re a nice low TDP out of the box, super efficient, and the cache disproportionately speeds up a few potential NAS specific workloads like encoding. It “hides” the performance penalty of cheap RAM. They’d also perfect for game servers.

…But don’t go out of your way if they're pricey.

How many drives do you want to use?