Nvidia Quadro P400 (2 GB RAM) (Pascal GP107 6th Gen NVENC chip):
*------------------------------*---------------------*
| Concurrent Sessions | 6 |
| Total Segs Transcoded | 180 |
| Real-Time Segs Transcoded | 180 |
| * Real-Time Segs Ratio * | 1 |
| Total Source Duration | 360.00000000000017s |
| Total Transcoding Duration | 39.94000854000001s |
| * Real-Time Duration Ratio * | 0.1109 |
*------------------------------*---------------------*
The P400 will cap out at 6 concurrent streams, it appears limited solely by its VRAM. A hardware mod to swap out for larger RAM chips might work, I could not find anyone who has done it. This card requires no power connector and is tiny consuming only about 30W though.
MSI GTX 950 (2 GB RAM) (Maxwell (2nd Gen) GM206 5th Gen NVENC chip)
*------------------------------*---------------------*
| Concurrent Sessions | 6 |
| Total Segs Transcoded | 180 |
| Real-Time Segs Transcoded | 180 |
| * Real-Time Segs Ratio * | 1 |
| Total Source Duration | 360.00000000000017s |
| Total Transcoding Duration | 39.78670270800002s |
| * Real-Time Duration Ratio * | 0.1105 |
*------------------------------*---------------------*
Similar performance here, caps out at 6 concurrent streams thanks to its limiting 2 GB RAM.
Looking at the Real-Time Duration Ratio, it appears both nv{enc/dec} chips are capable of more concurrent streams, but run out of RAM:
[h264_cuvid @ 0x68432c0] ctx->cvdl->cuvidCreateDecoder(&ctx->cudecoder, &cuinfo) failed -> CUDA_ERROR_OUT_OF_MEMORY: out of memory
[h264_cuvid @ 0x68432c0] ctx->cvdl->cuvidDecodePicture(ctx->cudecoder, picparams) failed -> CUDA_ERROR_INVALID_HANDLE: invalid resource handle