The NVIDIA GeForce GTX 1080 Ti is a mean machine based on NVIDIA's second biggest implementation of its "Pascal" architecture, the 16 nm "GP102" silicon. This is the same chip that drives the TITAN X Pascal. The GTX 1080 Ti features the same number of CUDA cores as the latest TITAN, at 3,584 spread across 28 streaming multiprocessors. There is some cost-cutting here, but none that is designed to lower performance - the chip has a slightly narrower memory bus at 352 bit; that's one memory chip less than what you'd find on the TITAN X Pascal. The total memory amount is hence 11 GB. A cluster of ROPs is also disabled, so you now get 88 ROPs (as opposed to the 96 ROPs on the TITAN). The memory chips are, however, clocked 10% higher to make up for the 8.3% narrower memory bus. This move also translates into cost savings due to the lack of a 12th memory chip and probably better yields for the GP102 chip.
The Gigabyte GeForce GTX 1080 Ti Xtreme Gaming is marketed under the AORUS brand, which Gigabyte created for gaming graphics cards with RGB lighting. It is built around a triple-slot, triple-fan thermal solution, featuring a large overclock to a base clock of 1607 MHz out of the box. Memory is overclocked as well, and the card is priced $50 over reference.