Plex can’t transcode 4k video fast enough but my server is very powerful

[Sittingmongoose]

I am having an issue where plex can direct stream 4k fine, no buffering at all to many clients at once. As soon as I try to transcode 4k(yes I know that ruins color), it buffers like crazy. Taullti shows it transcoding between .4-.6 but it reports using (hw) meaning it’s using my nvidia gpu. My cpu usage is only 10-18% and my gpu usage is about the same. Why isn’t it using all my cpu or gpu resources if it can’t transcode in time?? I have plex set to “hurt my cpu”, I also tried “prefer speed” and I have the quality set to the fastest speed.

My 1080ti in my game pc would use about 40% of the gpu when I was transcoding and like 30% of the cpu(which is a pretty new i7) but the igpu was turned off.

Here are my specs.

-running in Windows 10 native

-using newest version of nvidia drivers, windows updates and newest plex server and client(shield) software.

-dell r610 with dual Xeon x5690 cpus at 3.33ghz with 6 cores each and hyper threading

-nvidia Quadro p2000

-48gb ddr3 trichannel

-os is on new 2x512 ssds in raid 0

-media is on 4x5tb HD’s in raid 0

-plex is transcoding to a 32gb ram drive(yes is actually using it properly, I noticed a huge improvement in speed on my x264 transcodes, and I verified it was writing to it.)

-my lan is all new cat 6a Ethernet with new switches and two new ASUS 68u routers

-everything is hardwired

-gigabit fios with 800mbs upload

-it’s not my network or my hard drives because direct play has 0 issues.

I don’t understand why plex can’t transcode 4k hevc smoothly, I have way more than enough power to do it. What’s weird to me is when I begin transcoding it uses some cpu and gpu resources, but obviously not to the level it should be.

[darcilicious]

What’s the target client? My apologies if I overlooked that in your list of specs.

[Sittingmongoose]

It’s a shield running newest plex build, kodi 18 with plex do it too. So does my roku with plex and plex preview as well as my iPhone.

[Uh_Oh]

As I’ve read in previous threads, 4K will only transcode using one physical CPU. Your dual CPU setup is cut in half in terms of performance in this case. See here for facts provided by a Plex Employee: Plex will not use 2 physical CPU’s

Thus, your CPU benchmark is listed at around 8900 if you are overlcocked, or a more realistic baseline of around 7300 without overlocking.

Whether or not that is enough horsepower to transcode a 4K, I don’t know. But it is additional info that you didn’t have before.

[Uh_Oh]

When it comes to certain types of 4K transcoding, I believe that some formats can only use a single thread. In that case, your single thread rating is ~1,500. It might be that you need a single thread rating of over 2,000. I don’t recollect where I saw that info recently. I don’t house any 4K content and don’t have a server capable of doing so. Thus, this is only from memory.