Low CPU usage for rendering with new CPU

Forum|Forum|1 year ago
June 21, 2024
3 replies
2643 views

I used to use a custom-built PC with a i7-9700k CPU and RTX Quadro 4000 graphics card for Premiere Pro / Media Encoder. When using CUDA acceleration, I would render out a 2-hr video mp4 3 Mbps 720p, it would use almost 100% of the GPU and 100% of the CPU, and would take about 8 minutes to render.

I just built my own PC, and upgraded to an i9-12900k CPU, and kept the same GPU. My new system uses DDR5 RAM, instead of DDR4, and I now have nvme gen 4 disks instead of SATA, as bonuses. I was surprised to see that when I render the same video, it uses about 90% of my GPU, but only 25% of my new CPU, and the render time is still 8 minutes. Why isn't Premiere/Media Encoder taking full advantage of the more powerful CPU to cut down rendering time some more? Is this expected behavior? Thank you!

This topic has been closed for replies.

MyerPj

Community Expert

It's good you have a PP team member replying to you. I'll just say, it's easy to figure though. Your GPU must be the limiting factor. So, in the older system, your GPU was pumping out at about 100%, and to keep up, your CPU was at about 100%. Now you have the same GPU, but in order to keep up, your CPU only needs about 25% since it's much quicker. So, that's that.

If your source footage is not 720p, then your GPU would be used in the translation of the framesize.

integrityvideoAuthor

Known Participant

That is helpful, thank you. It's odd to me that Premiere won't take full advantage of the CPU to encode faster, so that both GPU and CPU are utilized fully.

R Neil Haugen

Legend

That assumption is something most of us start with before we learn that the CPU and GPU are radically different devices.

They do not use the same code, nor even the same mathematical operations. They are not in any way, shape, or form interchangeable.

When a process can be done on either, there is a decision tree to decide which tool is used, and then that tool's specific code in the program is used. There are completely different code trees fir aby job depending on which tool is used.

Few things are split between them at the same time. Because it just doesn't work to do so.

In your case, that new CPU is strong enough to get ahead of what the rest of the system can do. So it idles some.

Everyone's mileage always varies ...

mattchristensen

Legend

@integrityvideo It sounds like maybe your new system is using Hardware Accelerated Encoding to take load off the CPU and use the dedicated encoding blocks on your chip instead. When you are on the export page, look at the summary on the bottom right and see if it says "Hardware Encoding" or "Software Encoding". You can also manually choose this in the video export settings. Try turning off Hardware Encoding and you should see full CPU usage. It may or may not be faster, it will depend on your system and your sequence.

integrityvideoAuthor

Known Participant

Yes, I am using Hardware Accelerated Encoding. I was before as well with the old CPU. My question is why with the old CPU, I was using almost 100% (with Hardware Acceleration turned on), but now it's only 25%. Thanks!

integrityvideoAuthor

Known Participant

I will add that the videos contain no video effects. I'm just stitching mp4 video files together and rendering out as mp4.

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