Where is my transcode bottleneck?

Server Version#: Version 4.53.0
Player Version#: Roku

I moved Plex over to an i5 Windows box, 16 GB, SSD, 1050ti GPU. I was expecting this thing to provide plenty of performance to transcode one or two streams at a time. I’ll be surprised if I ever hit four at once. My media is stored on a Synology.

I’m testing this, and it’s pausing within 20 secs, and gives up after a few pauses. I grabbed some screenshots showing Resource Monitor, Task Manager, and the CPU and RAM usage on my Synology. Nothing is maxed out. I can’t figure out why it’s burning through its buffer.

I’ve tried two high bandwidth movies. One is 58 Mbps and the other is 72 Mbps. I didn’t grab screenshots of the 58 Mbps movie, but just eyeballing it, the graphs were very similar. According to the Roku Plex File Info, the 58 Mbps is HEVC HDR 10 and the 72 Mbps movie is H.264.

To test my network connection from the Synology to the PMS, I started a copy of one of the movies. It was able to sustain about 110 Mbps.

The spike in the GPU graph happens when Plex gives up and displays the message that it can’t continue. I can’t really tell if they’re precisely simultaneous, but they’re pretty close. Prior to that, when it’s just re-buffering, the usage remains flat.

I’ve searched around, and didn’t find any threads that seem to directly address what I’m seeing.

What am I missing? Why can’t this thing transcode even a single video at a time?

Edit: A little more info. I checked the PMS Activity tab and saw in the movie details that it did, in fact, have the HW icon indicating that it was using the hardware transcoder. Also, I found the directory that it’s using to cache the transcoded bits and watched them tick up, until it gave up. The cache is on the SSD.

Did I say something wrong? Leave something out? Can anyone point me at a tool or diagnostic that will help me understand why this machine can’t transcode a single movie, even though it had a decent GPU?

restart your server
play something were the transcoding fails
note the time of failure
post the logs here along with the time.

make sure verbose logging is disabled.

xml for the specific file played would also be helpful.

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