If this proves to be the real deal... oh boy... Looks a bit odd though...
Edit: So having had a better look, it looks like a rough draft of an Asus board, as it has a TPU, EPU, Aura and LanGuard, all Asus proprietary things.
I also don't understand why a new board like this would be equipped with FireWire, does anyone still use that? Note that a lot of things are seemingly just suggestions of what could go in the slots and the x8 slots are shared with the x16 slots.
Source:
https://www.reddit.com/r/Amd/comments/618blp/x399_and_x390_leak/