Dunno why you got a mATX mobo and a mid tower case, but yeah, you should be fine, as long as you put it in right. make sure the IP shield is snapped in and then put it in slightly at an angle, with the IO going in first. once its about lined up, flatten it out and make sure the IO is firmly in the holes. the stand offs should all be lined up except for the bottom 3. the center standoff is to keep it steady so that you can screw in the rest.