Pretty much every single modern game works great with SLI and it matters huge what resolution is being played. Sli'd 970`s blow the 980 out of the water, and if you are playing 1440p or 4k you will need and want the extra firepower. Here is a link to some benchmarks.... http://www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_9...
taken form http://www.tomshardware.com/answers/id-2308460/dual-gtx-970-sli-single-gtx-980.html