The SLI scaling on this game so far is crap, 2x 980 Ti's and it's hard to maintain 60fps at 3325x1871, even at 2560x1440. All settings maxed out (SMAA) and GPU usage on both cards vary around 60% on both to 80% on both but the frame rate may be around 45fps to 60fps.
This is with the latest 361.75 driver. This game needs a new SLI profile, a patch or both because something is not right.
For example at I could overlook that city at the beginning and be at 60fps both cards around 70% usage and it's silky smooth, then I head into the the first tomb where you read that Greek stone and the frame rate is around 45fps, even though the GPU usage on both cards is around 65% usage and CPU usage barley being used. There is bugger all graphics wise on some scenes to push a single 980 Ti yet two struggle to get to 60fps.
Thoroughly enjoying the game though, it looks stunning and the real-time cut scenes of Lara close up look amazing.