4K - Crysis 3
Crysis 3 is a beautiful-looking game that continues to tax high-end systems. We've benchmarked a 60-second section near the start of the game, with lashing rain, numerous reflections and full DX11 pomp on show.
Is Crysis 3 really that demanding or is it just poorly developed? Either way, it kills all of the GPUs at 4K. Heck, we've even disabled anti-aliasing and we're still nowhere near 30 frames per second.
Look up pain in the Nvidia/AMD dictionary and you'll probably see a screenshot of Crysis 3.
We've taken the time to measure the slowest one per cent of frames, but we'd needn't have bothered: the majority of frames are slow when trying to play this game at a lofty 4K resolution.