Go to https://www.noctua.at/en/products/nh-u12s/downloads -> Information sheet. This has got a tiny scale drawing of the cooler. Print this out but magnified to 1:1 scale, cut it out, and check directly if it fits. While this gives you just a profile, not the full 3D shape, it should still be sufficient as a check for this particular mainboard.
Furthermore, the Installation manual on the same web site shows you how the mounting frame is shaped. I wonder if there isn’t a collision of this frame with the backside heatsink of the mainboard. Depends on the height of the standoffs of the frame versus the height of the innermost step of the heatsink. From photos, it seems to me as if the relevant part of the heatsink is shallow enough there though. Unfortunately I am not aware of a method to verify this without the actual parts on hand.