Recently built a new PC and have 2x6970s in CF which are awesome. They work fine in 2D and 3D modes in all games. BUT when I play a DX11 game and enable tessellation card 2 artifacts badly...disabled CF and card 1 is fine but card 2 is the culprit. Both cards are at stock speeds, confused as to why its only tessellation that causes a problem...I assume this an RMA, but any suggestions?