Why OBS is using a significant amount of CPU when using NVENC?

[Fractale]

From my understanding, the composition of the different sources is done on the GPU and it's also the case for the encoding (NVENC) so what is left on the CPU?
I have a CPU bottleneck so I would like to know how I can influence the CPU consumption of OBS knowing I'm using NVENC encoding

 

[Lawrence_SoCal]

You misunderstand
NVENC handles the video encoding. All the rest is done by CPU... things like audio filters and effects, chromakeying, etc

You may want to make sure your Operating System is optimized for an under-powered system, then beware OBS settings that drive CPU. Some plugins, filters, effects take a lot more than others

 

[Fractale]

You misunderstand
NVENC handles the video encoding. All the rest is done by CPU... things like audio filters and effects, chromakeying, etc

You may want to make sure your Operating System is optimized for an under-powered system, then beware OBS settings that drive CPU. Some plugins, filters, effects take a lot more than others

thank you for your answer. regarding OBS, I'm only using game capture and a webcam. I don't use any filters or effects.
because the composition is done by the GPU, does canvas resolution and game resolution affect OBS CPU performance?

How can I optimize my operating system for my system (big GPU but underpowered CPU)? I currently close all the apps and boost the fans speed of my pc.

The game runs fine when I don't use OBS.

 

[Lawrence_SoCal]

because the composition is done by the GPU, does canvas resolution and game resolution affect OBS CPU performance?

No, composition is done on CPU - typically (I think) ONLY the rendering/encoding is offloaded to GPU [I could easily be oversimplifying though]

Understand that real-time video encoding is VERY computationally demanding. If your system is busy doing game play (or whatever else), you may be asking too much to add real-time video encoding as well. The easy (but costly) answer is to get a more powerful computer. So game runs fine, then start OBS (OR ANY OTHER similar software), and it slows down is perfectly normal for under-powered systems. Same as saying car works fine until hooking up at 5 ton trailer.

I recommend monitoring hardware resource (CPU, GPU, RAM, Disk I/O, etc) utilization [for ex. using Task manager’s Performance tab and/or Resource Monitor] to see if your system is being maxed out with your settings https://obsproject.com/wiki/General-Performance-and-Encoding-Issues and https://obsproject.com/wiki/GPU-overload-issues

How do you optimize your OS and OBS for under-powered? that is a whole art and science, unto itself. Sorry, you are unlikely to pay me a consultant rate to work through this and it would take way more time than I'm willing to volunteer. I've pointed you in the right direction. I'll let others here or you figure out how best to approach this for you