GPU not fully utilized and CPU fans keep spooling up

[emmanuel_shiu]

Hi,

I just received a new computer from Puget and when i try to work in RT with GPU node and RTX enabled, my cpu fans keep turing on and they're quite loud. When i look closer it shows (HWmonitor and GPU-z) the gpu being used about 50 percent and the cpu about 50 percent. I don't understand this as I've enabled GPU node and do not want to use the CPU. I would this the GPU should be pegged at 100 and leaving the CPU alone. Anyone have thoughts regarding this? Using in maya . Thanks

[nicolas_fuminier]

Hi emmanuel_shiu ,

First of all, I love your work,

I'm no expert in Vray GPU but I'm using it at our studio for about 2 years and I never been though your issue.
Do you have a single GPU ? 2, 4 ? What model is it ? 4090s ? I hear there was some early release issue with the 4090s (https://forums.chaos.com/forum/v-ray...w-in-rendering) but we only run 3090s here so i'm not quite familiar with the issue.
First I would look at the GPU driver (obvious but well, who knows). Recommended by Chaos is the 536.40 but you might need a specific one for the 4090 ( Muhammed_Hamed might help here)
But that's not explaining why the CPU is running that hight (i'm running between 25 to 30% CPU normaly). Specialy if you are in RTX mode where de CPU cannot be added to GPU calculation.
What does your Cuda graph in your windows task manager say when you hit render ?

Sorry, there are no real answer in my post, i'm just trying to narrow down your issue with some answers.
Best,
Nicolas

[Muhammed_Hamed]

Hi emmanuel_shiu and welcome to the forums, nice to see you here

Depending on your CPU, it is normal to see high CPU usage when rendering with V-Ray GPU. While the rendering process itself is on GPU, the CPU is still being used to feed the GPUs, then every sample is sent to the gpu, its results are gathered and modified by the cpu and then drawn. Around 30 to 50% CPU usage is expected roughly if you have a high-end GPU, and it could be higher if you have multiple high-end GPUs
Other than that, using Progressive mode is recommended, and the least amount of render elements possible. This will lower the CPU usage and improve your GPU usage drastically.
Could you please share more information about your hardware and scene?
How many render elements do you have? sampler type? number of GPUs and CPU type?and drivers used

Best,
Muhammed

[Muhammed_Hamed]

nicolas_fuminier Thank you for your help as always

[nicolas_fuminier]

nicolas_fuminier Thank you for your help as always

Thanks,
Apreciate as always.

I'm learning too. Digging into other issues is a good way to answers yours.
Today I Iearned that renders elements increase CPU usage.
I'll sleep smarter than yesterday

[s_gru]

here's a sample of what i get when rendering with two 4080's on an older machine. scene has light-mixer and denoiser. 25million polys or so.