I also have an matx build but i use a Lian LI pc-v359 case that is much smaller and sleeker.
https://www.google.com/search?q=lian+li+pcv+359&espv=2&biw=1920&bih=974&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj5zYKQ07rPAhWE_R4KHfLdAEsQ_AUIBygC#imgdii=kq-YdRhsBIMXNM%3A%3Bkq-YdRhsBIMXNM%3A%3B78FW0BfDvMkTGM%3A&imgrc=kq-YdRhsBIMXNM%3A