For what it’s worth, I’m just setting up a build with an Asus Proart X870E Creator Wi-FI motherboard and a Ryzen 9 7950X3D. ECC seemed to be enabled as best as I can tell.
I populated it with two 32GB Kingston KSM56E46BD8KM-32HA (5600 SPD ECC) ram modules.
It first started up in non-ECC mode at a memory speed of 5200 MHz (as might be the expected speed for the supported CPU and memory specs).
I updated the BIOS to version 0706 and went in to the BIOS and changed the ‘ECC Mode’ setting from ‘auto’ to ‘enabled’.
Memtest Pro now reports ECC mode is active. I was able to set ‘ECC injection’ to on, and the test periodically said it was injecting an error.
But I’m not sure how you tell if the error was actually injected or not.