RobCrezz :
gamerk316 :
But what happens when a single 970 starts to bottleneck on certain frames? That's when the problems with SLI/CF become apparent.
I dont understand what you mean by that?
When using AFR its only having to render half the frames a single 970. Are you referring to frame time variance?
No, SFR (Split-Frame Rendering) has two GPUs create a single frame. Neither NVIDIA or AMD support this mode these days, because it's very hard to manage. Both use AFR (Alternate-Frame Rendering), where each GPU handles either Odd/Even numbered frames. So GPU 1 does frame 1, and GPU 2 does frame 2.
http://docs.nvidia.com/gameworks/content/technologies/desktop/sli.htm
The issue is, while each GPU only has to do half the normal frames, there will still be those hard to process frames that take significantly longer to render. As a result, you can start running into problems once either card starts to underperform, which is quite apparent. So while SLI'd 970's may be excellent today, once we reach the point where 970's will individually start to lag, SLI will make the latency issues a lot worse, resulting in more stuttering then if you just went with a single, more powerful GPU.