Would a multi gpu setup with a pci-e 2.0 x16 and x8 bottleneck a pair of say, gtx 780s? I saw an article regarding that matter a few years ago showing that it makes virtually no difference whatsoever. How is that now? 

manny8127
Would a multi gpu setup with a pci-e 2.0 x16 and x8 bottleneck a pair of say, gtx 780s? I saw an article regarding that matter a few years ago showing that it makes virtually no difference whatsoever. How is that now? 

Not so much your PCIe bandwidth but, the newer platforms have up to a 15-20% performance advantage clock for clock depending upon whether it's a GPU or CPU limited title.  I'm running SLI TITANS and GTX 650Ti dedicated to PhysX and I keep up just fine.

I've done some testing on this with my 7950's and I've found that it doesn't really matter even when using a x4 pcie 2.0 lane.
In crysis 3 @ very high 1080p 2xsmaa (mgpu) I only loose 4-5Fps when running in a 4x lane vs an 8x lane (57fps).
And in cpu bound games (bf3) there is a 10-20fps decrease when running in a 4x lane but it still easily stays above 120fps so I don't notice any performance loss.