So I came across this issue with the heatkiller gpu x3 5x0 block where on some evga cards that don't have the gray heat spreader the waterblock does not make contact with the gpu. There is literally a 2-3mm gap between the gpu and the heatskink. After a bit of searching around it seems that a few other people experienced this issue with the heatkiller and koolance blocks. Rather than rma'ing right away I'm wondering if I could try a little thermal Pad tue fill the gap? How much of a Performance drop could I expect to see? I'd be ok with a few degree increase. I suppose I could try a thin Piece of aluminum or copper too. What do you guys think?