http://www.pcgamer.com/the-best-nvidia-geforce-gtx-1080-ti-deals/

The GTX 1080 Ti is the current king of the hill when it comes to GPU performance. All that power comes at a cost; however, it's worth noting that the GTX 1080 Ti not only outperforms the previous monster of the GPU world, the Titan X, it also does it for less money. 

The two have the same CUDA core count, and the GTX 1080 Ti has higher clockspeeds, meaning better performance. The memory speed is speedier, 11Gbps compared to 10Gbps on the Titan X, and the Ti has more memory bandwidth, despite having 1GB less VRAM and a narrower bus. Basically, Nvidia has pulled out all the stops with the GTX 1080 Ti, and that's why we like it so much in our review.