Most high end motherboards these days are aimed at gamers and so they include all sorts of RGB Led lights and assorted bling so that the users can install them in cases with a clear side. I don't care about all that.
The problem with this motherboard and card combination is that, as part of the bling, they have covered part of the board with a piece of plastic, marked as 'AMP-UP AUDIO', which has no actual function... and one end of that lies in front of the PCIEX16 slot where the graphics card needs to sit (see the arrow).
Here is the tab on the graphics card that is blocked. I don't know if other cards have this tab.
So with the plastic in place, you can't seat the card... and both components are from the same manufacturer... sigh
Fortunately, because the cover has no function whatsoever, you can just remove it and solve the problem. Flip over the motherboard and remove these two small screws. Throw the nasty piece of plastic in the recycling. Job done...