3DMark
3DMark is a multi-platform hardware benchmark designed to test varying resolutions and detail levels of 3D gaming performance. We run the Windows platform test and in particular the Fire Strike benchmark, which is indicative of high-end 1080p PC Gaming.
Ashes of the Singularity
Ashes of the Singularity is a Sci-Fi real-time strategy game built for the PC platform. The game includes a built-in benchmark tool and was one of the first available DirectX 12 benchmarks. We run the CPU-focused benchmark using DirectX 12, a 1080p resolution and the Extreme quality preset.
Grand Theft Auto V
Grand Theft Auto V remains an immensely popular game for PC gamers and as such retains its place in our test suite. The well-designed game engine is capable of providing heavy stress to a number of system components, including the GPU, CPU, and Memory, and can highlight performance differences between motherboards. We run the built-in benchmark using a 1080p resolution and generally Maximum quality settings (including Advanced Graphics).
Metro: Last Light Redux
Despite its age, Metro: Last Light Redux remains a punishing title for modern computer hardware. We use the game's built-in benchmark with quality set to Very High, SSAA enabled, AF 16X, and High tessellation.
Gaming titles tend to be a little faster for ASUS' Crosshair VI Hero compared to Gigabyte's cheaper AX370-Gaming 5. GTA V rounds up to a higher average frame rate value while 3DMark Fire Strike scores nearly 500 points (around 2.5%) more on the ASUS motherboard.
On the M.2 socket you mentioned an ugly green one, I think anyone buying this board will opt for the Samsung 950 or 960 which are a matching black.