The GeForce GTX 1070 Ti is a frontal assault on AMD's Radeon RX Vega lineup, it will have a performance level that will be closer to the GeForce GTX 1080 than the GeForce GTX 1070.
The latest card is a new variant of the GP104 GPU with 2432 CUDA cores enabled, this compares to 2560 CUDA cores on the GeForce GTX 1080 and 1920 on the GeForce GTX 1070. The base clockspeed of the GeForce GTX 1070 Ti is said to be 1607MHz, the same as the GeForce GTX 1080, but the Boost clockspeed will be a bit lower. The GTX 1070 Ti has a Boost of 1683MHz, whereas the GTX 1080 has a 1733MHz Boost.
In terms of memory, the GeForce GTX 1070 Ti will stick with GDDR5 but it will be clocked higher than the memory of the GTX 1070. Unfortunately for gamers, these specifications may make it an attractive option for cryptocurrency miners.
Various NVIDIA AIB partners are working on their own cards so there's a good chance we'll see custom designs on launch day. The photo from two weeks ago showed a system with the ASUS STRIX GTX 1070 Ti so we know those cards have been out in the wild for at least two weeks.