eGPU hacking part 2, PCIe Gen3

So! I was sadly dismayed that my new msi laptop was advertised with thunderbolt 3 did not infact have thunderbolt 3. The laptop has worked well and pursuing a return and finding another would be quite the pain so instead for now, i just want to investigate other possibilities for the future. The 1060gtx in it will last me for quite some time and I wanted the thunderbolt 3 as an option for future proofing down the road.

For now, there has been all sorts of discussion and realworld testing on getting video cards to work off standard pci express connections inside the laptop. These have all been 1x connection designed for storage and networking, and are not the best suited for video cards, but for older computers even a 750gtx was a vast improvement. However when your base is a 1060gtx, that stuff is all moot.

Fast forward to today, while the advancement to thunderbolt 3 offered a much easier and more realistic upgrade path for eGPUs, the PCI express ports also got an update to gen3 which is 4x speeds. So here we are in the same boat, not all laptops, even gaming laptops are sporting the intel chipset for thunderbolt 3, but they are offering up PCIe Gen3 ports. So now comes the question of hooking high end video cards to the PCIe Gen3 slot of a laptop.

From my quick searches, a 1080gtx looses very very little performance stepping down to a Gen3 8x port. But I havn't been able to find anyone benchmarking for ****s and giggles what its like bottle necked at 4x speeds. Also would a PCIe Gen3 to eGPU require all new cables and card edge connector? I think the pinouts are pins on the edge connector are the same and its the protocol that scores the 4x speed improvements, but things like connection quality grade might need a bump as well.