http://www.tomshardware.com/reviews/gaming-graphics-card-review,3107-7.html

@Mossimo64001: If you check the Hierarchy chart above, GTX-690 is rated among the GTX-980 & Titan Black. The performance difference is not too significant considering the difference in costs. Each card is already running Sli since it has 2 GPUs and having another GTX-690 make the system run in quad Sli configuration. My initial design is to run 2 Titan Blacks but due the high costs during the build it is not practical beside the 2 GTX-690s will still do the job great if not better. If you offer me 18k I will throw in a 40inch Sony Bravia HD LCD. I'll Get back to you regarding the GPUs, I still have 2 GTX-690s on hand but that's for another build. I'm going for an IN-WIN S-Frame. Check it out it's an awesome case.