In the near future I’d also like to try one of my X470D4U units with TrueNAS Scale.
Just to be sure:
Since you’re using a Zen 2 Ryzen there shouldn’t be an issue going to the latest BIOS version, that’s currently version 4.28 and the latest BMC/IPMI firmware version is 3.04.04:
ASRock Rack is unreliable updating their public websites regarding BIOS and firmware releases, many users have to fend for themselves…
For reference:
I’ve been testing mine with that updates with Windows 10, a 3700X, 4 x 16 GB ECC and various NVMe and SATA SSDs and so far absolutely no stability issues.
If that’s different with TrueNAS Scale I should be able to complain soon enough