. . .The *effective* bandwidth of PCIe 3.0 is 985 MB/s per lane = 15.39 GB/s @ x16. To use it all, a single GPU running a 1080p monitor would have to achieve 1,992 frames per second.
Well, good to know I so desperately "NEEDED" those 40 lanes of PCIe 3.0 on these Socket 2011 mobos. I might actually use all that bandwidth in 20 years!