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 is well-tuned to take advantage of multi-GPU setups. Sure, £850 is a heck of a lot of money to spend on merely the graphics, but the results are impressive. We see over 80 per cent scaling at the 4K Ultra preset.