cuda initialization error api after 6 streams

now it is strange problem
currently doing 6 encodings quadro m2000. No problem with up to 6 streams.
If I open one more stream, cuda will not allow it. give the following error. There is no problem up to 6 streams.
Please help m

±----------------------------------------------------------------------------+
| NVIDIA-SMI 390.48 Driver Version: 390.48 |
|-------------------------------±---------------------±---------------------+
| GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. |
|===============================+======================+======================|
| 0 NVS 315 Off | 00000000:73:00.0 N/A | N/A |
| 30% 42C P8 N/A / N/A | 870MiB / 963MiB | N/A Default |
±------------------------------±---------------------±---------------------+
| 1 Quadro M2000 Off | 00000000:D5:00.0 Off | N/A |
| 56% 43C P0 29W / 75W | 1058MiB / 4043MiB | 5% Default |
±------------------------------±---------------------±---------------------+

±----------------------------------------------------------------------------+
| Processes: GPU Memory |
| GPU PID Type Process name Usage |
|=============================================================================|
| 0 Not Supported |
| 1 3274 C /root/bin/ffmpeg 167MiB |
| 1 3276 C /root/bin/ffmpeg 167MiB |
| 1 3802 C /root/bin/ffmpeg 167MiB |
| 1 3804 C /root/bin/ffmpeg 167MiB |
| 1 3811 C /root/bin/ffmpeg 167MiB |
| 1 4043 C /root/bin/ffmpeg 167MiB |
±----------------------------------------------------------------------------+
root@ubuntu:~# nvidia-smi dmon

gpu pwr temp sm mem enc dec mclk pclk

Idx W C % % % % MHz MHz

1    30    45     6    11    36    31  3304  1227
1    30    45     5    10    35    31  3304  1227
1    31    45     5    10    36    31  3304  1227
1    28    45     6    10    35    31  3304  1227
1    29    45     4     8    36    31  3304  1227
1    33    45     7    14    37    32  3304  1227
1    31    45     9    17    38    33  3304  1227
1    32    45     8    15    37    33  3304  1227
1    28    45     6    12    37    32  3304  1227
1    28    45     6    12    36    32  3304  1227
1    32    45     6    11    36    32  3304  1227
1    30    45     6    12    36    32  3304  1227
1    32    45     6    11    37    32  3304  1227
1    32    45     6    11    37    32  3304  1227

Duration: N/A, start: 45158.724533, bitrate: N/A
Program 1
Metadata:
service_name : 24 HD
service_provider: TURK MEDYA
Stream #0:0[0x13bf]: Video: h264 (Main) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 50 tbr, 90k tbn, 50 tbc
Stream #0:10x1423: Audio: mp2 ([4][0][0][0] / 0x0004), 48000 Hz, stereo, s16p, 256 kb/s
[AVHWDeviceContext @ 0x437f940] Could not initialize the CUDA driver API
[h264_cuvid @ 0x4061380] Error creating a CUDA device
cuvid hwaccel requested for input stream #0:0, but cannot be initialized.
[h264_cuvid @ 0x4061380] ff_get_format failed: -1
Stream mapping:
Stream #0:0 -> #0:0 (h264 (h264_cuvid) -> h264 (h264_nvenc))
Stream #0:1 -> #0:1 (mp2 (native) -> aac (libfdk_aac))
Error while opening decoder for input stream #0:0 : Operation not permitted