All ASRock AMD boards (or nearly all, but I haven't found any exceptions) support ECC memory. I'm not sure about Asus' X570 line since they market a board with

All ASRock AMD boards (or nearly all, but I haven't found any exceptions) support ECC memory. I'm not sure about Asus' X570 line since they market a board with explicit ECC support, but their lower-end and mid-tier X470 boards supported ECC. Their higher end boards -- curiously -- did not. You can generally tell if a board supports ECC by looking at the board's manual. If it supports ECC, it will be mentioned.