Im looking to speed up my editing process. My current bottleneck is the GPU. I have a Zotac GTX 960 AMP Edition, would throwing another of the same card in SLI, or even on its own benefit my editing speed? What about a different GTX card with or without SLI? There seems to be a ton of information about this for gaming, but none really talking about content creation. I also use Photoshop and indesign a lot, so any benefits with those programs in mind would help out a lot.
SLI is not related to GPU acceleration. SLI is strictly scaling frame draws across more than 1 GPU. GPU acceleration scaling across more than 1 GPU is configuring the GPU's in independent configuration. So simply add the 2nd 960 GTX card and the applications that support scaling for GPU acceleration will use it.