also from what i read on various forums, using a video card at 8x is no different then using the video card at 16x. This of coarse gets thrown out the window when you use eyeifinity/surround 3d with multi monitors and high resolutions.

I do believe if you are just gaming with a 1920x1200 resolution and below on ONE monitor, you will not see a difference in speed. Not too sure about multi-monitor non-eyeifinity/surround 3d setups though.