Also, if you are talking about a punched/raised metal part of the case plate in some mounting positions, and no raised metal, but just a screw hole in other positions, then you need the little plastic standoffs for the screw hole(not the raised metal), and you should just use a screw on the raised metal on the plate.
Raised metal only(looks like a hump on the plate) = just a screw to the motherboard
Drilled hole only(metal is flat) = plastic standoff + screw to the motherboard.