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.
Sapphire's super-high clocks give it a decent lead over the other two overclocked R9 280X cards, and it's the first time that a single-GPU AMD card has broken through the 8,000-mark barrier at the default setting.