If this communications is very fast it could be one explanation why AMD is even or sometimes have a bit better numbers on some tests when they test single threaded games on very high detail and high resolution.
Ok... there is not a good explanation for this... even Lost Planet, at higher resolutions, shows AMD can support higher FPS in GPU bound scenarios... but if you followed the thread. I can get the Intel's high res GPU bound FPS to exceed AMD's by increasing the PCIe frequency (i.e. the BW of the PCIe bus).

My hypothesis is that the AMD implementation of PCIe 2.0 in the chipset is better than Intel's.

jack