To be fair, i like Supermicro more then Asus.
The Non standard mounting is especially noteworthy when you have fixed standoffs that you can't remove without tools and force, since you can't simply have it not populated.
The most obvious non standard hole is the one top left above the IO.
Around the PCH is also where SM likes to differ strongly which sometimes causes weird problems when you forget a standoff behind there.
Happened to me a few times.