Thanks, Huddy. It's good to know it's a tested method. Will it matter if the pads cause the contact between fins and card to be constant? At the moment it's intermittent, but once I add the padding, it may be thick enough to cause constant contact. I'm basically asking if I should use thin pads or thicker pads.
Why don't you figure out why it's moving ? You can't be supporting the cooler with the GFX card which is what will happen if you fill the gap with something.