luckymatt42
I think it does not fit. Normally the mobo have a first pcie (1) and then the PCIe (16) precisely to allow double width.
In this mobo the pcie (16) is the first one on the left and I believe that the double card will collide with the three audio terminals on the back plate.
https://www.asus.com/latin/Motherboards/H81MK/gallery/