In the Futuremark results database several entries of the Geforce GTX 1080 Ti have been spotted. It is not exactly a hard product series to seek with it's unusual 11 GB graphics memory. The scores are based on Time Spy results.
The card is compared with Titan X (OCed at 1772 MHz) with memory at 12251 MHz. In that configuration the 1080 Ti is able to beat that card and config with a graphics score of 9049 points (I am referring towards the GPU score here btw).
The 1080 Ti shows a 1481 Mhz clock frequency and 1376 Mhz on the memory, this card scores 9239 points. There also is an entry to be found with the card tweaked to 1860 MHz, here the cards cores 9303 points. That tweak does mean it would boost over 2000 MHz. Check for yourself here.
Update: there is also a scoree spotted with the card overclocked seriously, scoring 10952 in Time Spy .. not bad! :) That card is the GTX 1080 Ti ast 2062 MHz (Boost) with memory at 5702 MHz.