I keep reading that GeForce GTX series of NVIDIA GPUs are limited by the driver to no more than two simultaneous sessions when hardware transcoding, and to have more, one needs a Quadro P2000 card or better. The article often cited as the source is https://developer.nvidia.com/video-encode-decode-gpu-support-matrix
I have an 8-core Intel 5960X CPU in my Plex server PC which doesn’t support Quicksync as it has no iGPU built-in. I also have an NVIDIA GTX 950 graphics card. Hardware acceleration support is enabled in Plex under Servier -> Transcoder settings. I’m using Windows 10 (64-bit) with all the latest updates and the latest NVIDIA GeForce driver delivered by Windows Update. I can easily get more than 5+ HW transcoding sessions going simultaneously without any noticeable loss of performance, so how is this possible? I can see, when I check the “Now Playing” tab for Plex, that these are all hardware-assisted transcodes, denoted by the (hw) tag in the Video Transcoding info.
Any idea what’s going on here? Does the ‘two concurrent sessions’ limit mentioned in the NVIDIA article not apply here, because all Plex transcoder threads are counted as one session?
Must be. I just replicated your experiment with slightly different hardware - Dual E5-2670 v1 CPUs, so no quicksync, and a GT 1030. Did four transcodes at once with no appreciable overhead, while a software-only transcode for one shows a noticeable impact in CPU activity.
That’s also strange since GT 1030 doesn’t support hardware accelerated encoding/decoding (NVENC), so you should be seeing the CPUs doing all the transcoding.
Can either you or @ekotan confirm that you saw “(hw)” for both the decode and encode portions of Now Playing? I have a GT 1030 sitting here idle and I’m tempted to try to replicate your experiment. It’s always possible that nvidia quietly (or accidentally?) enabled full NVENC in drivers or firmware.
I saw HW for both of encode and decode portions on more than two streams simultaneously with a GTX 950. Since then, I have switched to a Quadro P2000 card (for reasons unrelated to Plex) which supports unlimited NVENC streams anyway, but it was definitely happening with the 950 card, too.
Just an FYI. I put my GT 1030 into my Plex server to give it a test, and it only gives a (hw) for the decode portion, not the encode portion. So it looks like NVENC is still unavailable on the 1030.
On the bright side, it does still reduce the CPU overhead a bit.
Using Windows 10. If I get a chance soon, I’ll try transcoding a file with the card in the machine, and without, and compare the results for fun. Encoding is usually the taxing part, but I’m a little bit curious.
