3DMark
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.
The highest shipping frequency we've seen on a GTX 770 gets KFA2's LTD OC off to a good start; it's the pick of the bunch in terms of synthetic performance.