I currently use an Intel Xeon E3-1270 (5,390 PassMark CPU score), which transcodes 8 Mb/s 1080p 10-bit x265 files just fine.
However, I’m considering re-ripping to 22 Mb/s 2160p 10-bit x265 files.
What kind of CPU would I need to transcode such content?
I’ve already seen that but my content is 4K HDR 22 Mb/s 10-bit, so is a bit of a mix of those guidelines listed.
Interpolating, I can presume around 8,000-10,000 PassMark CPU score?
Probably more, because you usually have TrueHD Atmos with this kind of content, which also requires considerable processing power to reduce down to stereo when needed.
If you use subtitles, you have additional need for processing power.
Another consideration is tonemapping, which also is a major CPU load.
If you then also have to cater for more than one playback at a time, you want to have plenty more power on tap.
See the last paragraph of the linked article. If you go with a top of the line Intel CPU with Quicksync, you can reduce the load considerably with hardware supported transcoding (Plex Pass required).
Great answer… and who’s paying the electricity bill? PLEX?
King_Mustard: I have a NUC serving with Core i7-8559U, which is low in power consumption, and I have to turn off subtitles since PLEX always tries to render them otherwise and then starts transcoding video… and the my cpu goes up to 100%, video stutters and crashes after
a few seconds… totally anoying…
I quess you need at least Core i9-119xx or a GPU with powerful HEVC De-coding (GTX 1660 or faster), which means a lot of power consumption. Pretty expensive for PLEX not getting it done…
PLEX: you should try to use VLC instead of crappy EXO player or at least keep the option for us users to change Players. I have tried VLC with SMB networking sharing and there you go: no problems.
Seems to me that something isn’t right in your system. My NAS with an Intel J4125 can transcode 1-2 4K non-HDR files down to 8Mbps 1080P just fine, and significantly more 1080p streams without issue. This is even with basically my entire library be moderate to high bitrate HEVC files.
Your NAS has hardware transcoding active, even without Plex Pass. That’s why.
Right, my response was directed at AIUzzo who has Plex Pass and should be hardware transcoding also, not the OP. I think you explained very clearly to OP what he needed to do. I wasn’t trying to step on your toes Otto.
I have hardware transcoding on… but as I told before when playing 4k with subs either on FireTV Stick 4k or LG Plex App CPU load goes trough the roof, video stucks… Plex even tries to render SRT, which actually is no need to… and after 1-2 Minutes App/Player and some times even Server crash due to extrem CPU and RAM load… to me it looks like really crapping coding and since my tryout with VLC showed me It’s no a hardware problem - neither network nor Server. My guess is PLEX FireTV-App has really some bad, bad issues… and since I had a look at the EXO player wich PLEX uses and that programm (EXO) is, sorry to say so, a ■■■■ load of high end crapping coding… yeah well… I am happy it works somehow… but the moment anyone puts a real competitive solution to PLEX on market I guess I’ll be gone (as probably many others)
btw: I am talking about 4k UHD HDR files, disregarding TrueHD or DTS-X… Dolby Vision is not supported by PLEX (I have come up to realise that already)
https://www.cpubenchmark.net/cpu.php?cpu=Intel+Core+i7-8559U+%40+2.70GHz&id=3302
This CPU is probably at the brink when you activate (image-based) subtitles.
If the OS is set up correctly and you can actually use the Quicksync unit in the CPU, you should be able to transcode non-HDR 4K successfully with it.
Tone mapping from HDR to SDR is out of the question though. So don’t even try it.
You can lower the likelihood of transcoding by replacing PGS and VOBSUB subtitles with SRT versions.
And also insert AAC stereo audio streams before the DTS HD MA or TrueHD streams.
That way clients will by default pick the AAC streams and the surround streams are still at your disposal for local playback in powerful clients.
Done all of it - does not work 
Have to turn off subs, even SRT
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