mATX is smaller mobo, ATX is larger. Power conncectors are the same. Standard ATX PSU sometimes won't fit in the small cases built specifically for mATX mobos. But almost all std. ATX cases will have proper mount points for mATX mobos.
That's the way I have mine - ATX case, mATX mobo. My mobo came with a proper backplate that snapped right in.
.bh.
Where's the :sun: ?