Hi. I'm wondering how those little paper washers should be placed when installing a motherboard.

I have been told that:
(1) they should go between the motherboard and the screw posts on the case, to insulate the motherboard from the case (this means they go underneath the motherboard, but it's very difficult to get them to stay there while you install)
(2) they should go on the screws before you pass them through the holes on the motherboard to screw it down (this means they are on top, between the screw head and the motherboard)
(3) that either method is fine, but that you should use them
(4) that they aren't necessary at all

help appreciated, thanks