Re: PCIE gen 4 will it have an effect in crypto mining?
The PCI-E extenders can run at PCIE 1.0 X1 with no hashrate drop. What makes you think that you will benefit from PCIE 4.0? 
In current technology and algorithm yes, it will not benefit from it, but what I am saying is that in the future if developers adapt and make improvments can this technology be beneficial?