I currently have a single Powercolor PCS+OC R9 290 and want to add a second R9 290 preferably a second Powercolor PCS+OC R9 290 if I was to put 2 of these in the x16 and x8 slots of my Asus Maximus VI Formula there will be about 3mm of clearance between the backplate of the card in the x8 slot...