The bottleneck is not PCI-Express, not even the 3.0 version. The bottleneck is shipping processors with just 16 PCI-E 3.0 lanes (!). Things are changing with th

The bottleneck is not PCI-Express, not even the 3.0 version. The bottleneck is shipping processors with just 16 PCI-E 3.0 lanes (!). Things are changing with the new high end desktop processors, with 64 PCI-E 3.0 lanes (e.g. AMD Threadripper [1]), which is massive: 128 GB/s, and hardly a bottleneck. The 4.0/5.0 versions will allow reducing costs by requiring less lanes, thus using less pins, being cheaper to produce. [1] http://www.tomshardware.com/news/amd-threadripper-vega-pcie-lanes,34581.html http://www.tomshardware.com/news/amd-threadripper-vega-pcie-...