corsair 750d motherboard help

[Liamjmull]

My corsair 750d case came with only 1 standoff which it was supposed to. The case itself has raised holes where the standoffs should go but when I add standoffs the motherboard io doesnt line up as it is raised which leads me to beleive that I do not need to add standoffs as the raised holes act like standoffs themself and they are built in
am I correct?

 

[Liamjmull]

I believe it is called a convex outcave