make sure you used the mb brass standoffs. they give the mb space not to short out on the case. also when installing a mb dont screw the first few screws down tight. with most cases you have to adjust the mb a bit so that the video cards/extra cards have room to drop into the case slots. with large video cards you need to remove two of the back case slot covers then line the video card up with the top pci video slot. one closest to the cpu. when it falls into place it lock in with a clip and a small snap. witrh most cards you have to line up the video cards/extra cars to fit into the back case slot covers.