The Performance-Per-Watt Of NVIDIA Fermi To Pascal, AMD R700 To Polaris Benchmarks
As another game that can be easily tested on all of the hardware was Valve's Portal game...
With Portal the performance-per-Watt puts AMD's latest Polaris and Fiji cards as more competitive with NVIDIA's Maxwell and Pascal, but the GTX 1060/1070/1080 still have a much stronger showing. With Portal the perf-per-Watt when going from a GTX 460 to GTX 1060 on these latest Linux drivers is up by 7x! With the AMD hardware going from the HD 4890 (RV790) to R9 Fury is a 7.8x improvement.
The CPU usage when using the NVIDIA driver with OpenGL is indeed higher than the AMD Linux driver stack.