Nvenc session limit per GPU
Nvidia limits it 2 per system Not 2 per GPU. The limitation is in the driver, not the hardware. There have been unofficially drivers posted to github which remove the limitation
I'm using Imageio, the python library that wraps around ffmpeg to do hardware encoding via nvenc. My issue is that I can't get more than 2 sessions to launch (I am using non-quadro GPUs). Even using multiple GPUs. I looked over NVIDIA's support matrix and they state only 2 sessions per gpu, but it seems to be per system.
For example I have 2 GPUs in a system. I can either use the env variable CUDA_VISIBLE_DEVICES or set the ffmpeg flag -gpu to select the GPU. I've verified gpu usage using Nvidia-smi cli. I can get 2 encoding sessions working on a single gpu. Or 1 session working on 2 separate gpus each. But I can't get 2 encoding sessions working on 2 gpus. 
Even more strangely if I add more gpus I am still stuck at 2 sessions. I can't launch a third encoding session on a 3rd gpu. I am always stuck at 2 regardless of the # of gpus. Any ideas on how to fix this?