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 slightly overclocked Sapphire Radeon R9 270 Dual-X does a very good job at imitating the Radeon HD 7870 in this synthetic benchmark. As usual, Nvidia cards tend to lag a little behind the price-comparable AMD competition.