While there is a standard ATX connector design for the back of the motherboard, each manufacturer can layout the connectors however they need to. This means that the basic ATX connector face plate will need to be removed from the case and the custom one that ships with the motherboard be installed.
To remove the basic ATX plate, gently press in on the corner of the installed ATX plate until it pops out. Repeat this on the opposite corner to fully remove the plate.
Install the new ATX place by aligning the connectors properly (PS/2 keyboard and mouse should be on the side towards the power supply) and gently pressing from the inside until it snaps into place.