https://videocardz.com/67004/first-overclocked-geforce-gtx-1080-ti-3dmark-benchmarks-leaked
"According to screenshots, the GTX 1080 Ti was running at 2062 MHz with memory at 5702 MHz. It’s hard to say what is the actual boost clock of GTX 1080 Ti right now, but I saw samples running at 1860-ish MHz, so that would roughly be a 200 MHz overclock."
That's roughly 10% higher than what a stock Titan gets in FireStrike.