3DMark Fire Strike
3DMark is the latest version of this hugely-popular synthetic benchmark. Making use of DX11 features such as tessellation, compute shaders and multi-threading, it provides modern-day results and is available as a free download.
3DMark shows that there is very little difference between the Titan X and GTX 1080 Ti. The two could be the same card, given the variability of boost, and both are 20 per cent faster than a well-overclocked GTX 1080.