I know the regular 980 was, at least in this game. And 980 Ti is even more powerful. So what happens when you game with two of these in SLI on a mainstream 115x system with limited pci-e b/w (8 lanes for each card)? Surprised nobody has come up with a comparable test yet. Discuss!
Hint:
suing Intel isn't an option
Intel? Intel provides sufficient lanes on their X99 motherboards or even Z170. The bottlenecking will be almost non-existent.
If you have 980Ti SLI, and you are running 1080P/1200P, you will be CPU limited MUCH more than PCIe limited. If you are running 1440P/4K, you will be GPU limited MUCH more than PCIe limited.
Usually when people switch platforms from an older gen i5/i7, they start assuming they were PCIe bottlenecked when the huge performance boost they are seeing is coming from a higher IPC and much faster CPU architecture, not PCIe lanes. Overall, 3-4% isn't a bottleneck. If you want to get math picky, an upgrade from i7 4790K to 6700K OC would provide a greater boost in minimum fps than moving from PCIe 2.0 x8/x8 SLI to 3.0 x16/x16. Micro-stuttering, SLI/scaling profiles, and enough CPU speed at lower resolutions or enough GPU horsepower at higher resolutions is the big factor.