I have noticed on some shows that I have on my NAS (.mkv format) the CPU tends to max out from plex and that it will dramatically drop the quality of the video from 1080 down to 480 even tho I have a wired connection to it and I only see it happen when the CPU maxes out on the NAS so the only thing that I can thing that would cause this would be the Transcoder since that is CPU intense as it currently is but when I run the show directly from my computer using MPCStar it barely even touches the CPU so that makes me think that the Transcoder could use some improvements to be able to help everyone out
I am using a Synology DS1815+ if that helps
That’s all to do with using the device your using as a server (your nas) and nothing at all to to do with the MKV container. I have around 50TB of data and its almost entirely made up of MKV files. There is no issue at all with transcoding 4 or 5 mkv files on an i7 with software decoding although granted the CPU will peak often. Then again if it’s a recent intel with hardware acceleration there’s no issue with transcoding 4 or 5 streams with barely any CPU activity and that’s just with an i3.
Options
Convert media to something your NAS likes.
Use a proper server device.
Look around here https://forums.plex.tv/categories/synology for advice.
well i have no idea what cpu it is only that it is Quad Core 2.4 GHz and given it is an older model it wont be recent hardware this only seams to be a problem with 1080p mkv files when running a mkv it keeps the cpu maxed at all times not just hear and their
@HitsVille said:
Options
Convert media to something your NAS likes.
To be clear, xplazma would have to convert the media to a container, resolution, video stream format, and audio stream format their playback client can direct play.
@xplazma
Plex server is made to transcode so you don’t have to worry about containers/formats/resolutions and what playback device you are watching on.
If you’re watching on something that doesn’t like what you are feeding it, Plex transcodes.
If you server doesn’t have enough CPU horsepower to transcode 1080p (seems yours doesn’t), you have the issue you are experiencing.
Your CPU is a Intel Atom C2538 2.4 GHz
Few Atom processors have the raw horsepower needed. Great for backups/storage/low power use, not great for transcoding.
I also searched for your model to see if it had hardware capable acceleration using QSV. It does not.
@JamminR said:
@HitsVille said:
Options
Convert media to something your NAS likes.To be clear, xplazma would have to convert the media to a container, resolution, video stream format, and audio stream format their playback client can direct play.
Exactly. But he has another option?
I truly despise MP4, but MP4 with AAC seems to be his only option short of upgrading his server hardware…
Sorry I’m clearly missing the point you’re trying to make to me.
@HitsVille - Since the server cares less about what’s on it (MKV) than the client does,
I’m trying to say that "Convert media to something your NAS likes. " might be better said as “Convert media to something your player likes” to fit better and be more clear.
Yes, it’s more complex than that, especially if more than one type of player is used. (Hence why Plex wants raw transcode power though, that many NAS usually don’t provide), but I wanted to make sure xplazma knew the difference due to them already thinking NAS didn’t like MKV.
@JamminR said:
@HitsVille - Since the server cares less about what’s on it (MKV) than the client does,
I’m trying to say that "Convert media to something your NAS likes. " might be better said as “Convert media to something your player likes” to fit better and be more clear.
Do’h. Even after you pointed it out the first time I still didn’t spot it. My bad. 
Early 2021 clean-up: implemented (might require sufficiently powerful server)
