Can I use ECC UDIMMs with a Ryzen 5 5600X on a B550 motherboard?

Yes, ECC UDIMMs will work with a Ryzen 5 5600X on B550, but motherboard support varies. The CPU supports unbuffered ECC, but each B550 board manufacturer must enable it in BIOS—some do, some don’t. Check your board’s QVL list or manual for ECC UDIMMs; if listed, you’re good. For guaranteed support, look for boards explicitly advertising “ECC support,” like some ASRock or Gigabyte models. Don’t use registered or LRDIMMs—they won’t work.