Make sure the video card drivers are up to date - don't use the ones on the CD that came with the graphics card. Also. is the video card installed in the top blue PCIE slot or the bottom black PCIE slot on your motherboard? The top lane is 16x, the second lane is only 4x.
My Nvidia drivers are up to date and I made sure to use the uppermost blue pcie slot... I'm not sure what it could be then.