This adapter runs only one of its slots on the old mainboard’s BIOS, so it CANNOT be used to boot system on this adapter as I expected. But when I use it for storage, it’s OK. I think it would be better on mainboards at least model 2018 or later.
Lastly, it made by Dell so I don’t have to worry about the poor quality or backdoor may come from some cards that are made by CHINA manufactures.