How many NVIDIA NVENC engines a particular GPU have? There is a NVIDIA VIDEO CODEC SDK APPLICATION NOTE - ENCODER in which we can read the following:


  While Kepler and first generation Maxwell GPUs had one NVENC engine, certain
  variants of the second generation Maxwell GPUs and Pascal Generation GPUs have two/three NVENC engines physically present on the silicon.


So, does anyone know how to determine the number of NVENC engines in a GPU or already know the numbers? Because there is no information in NVIDIA datasheets and they are annoyingly silent in their own developer forums.
Since you are actually more interested in performance (Frame Per Second) than in the NVENC engines count, please consider my below rounded up figures.
I've compared GTX 1060 and GTX 1080 only.


H264, GTX 1080 encodes 70%  faster than GTX 1060
HEVC, GTX 1080 encodes 140% faster than GTX 1060