If you are installing a backplate to a video card you will have to use the screws provided with the backplate to attach it.  It will have rubber spacers on the backplate to prevent the it from shorting the card.  Cards that come with a water block are not designed to work with a backplate and will not attach with the screws privided with the backplate.  The pad on the backplate transfers the heat to the plate.  It may be neccessary to remove a foam strip on the card.  This does not void the warranty.