[Sanddancer]

This is where it gets complicated, because both the chipset and the processor have their own set of lanes. Skylake, and the 100 series, have 16 lanes from the processor, and up to 20 lanes from the chipset, with the chipset only able to aggregate in groups of four. The chips that use the x99/c61x chipsets have 28/40 lanes on the CPU, and have up to 8 lanes given by the chipset. So a hypothetical Broadwell-EP Mac Pro would not be stymied by the chipset, as it gets most of its PCI-e lanes from the processor already, and would see a significant performance boost compared to the current processors, given that the high end chip from then is about middle of the road in Intel's current lineup.