RTX 3090 GPU load Drops

[FranklinTre]

Hello there,

I noticed something weird with my new RTX 3090. The GPU Loads has drops every 1 minutes for 1 to 3 seconds. I can see that in GPU-Z and in AfterBurner, and I can hear that cause the fan speed is dropping too. The GPU is a bit overclocked but even with sotck parameters the thing happen.

This thing does not happen with other software so I suppose it's a Vray or 3DS Max thing.

Any explanation ? Is it normal, the way Vray does calculations ?



Windows 10 64bit

Vray 5
Nvidia Driver Studio 460.89

[FranklinTre]

To complete my test, I tried on different software using the 100% GPU load.
In OctaneBench there is nothing, is 100% all the time with no drops, but I noticed that it's not using the entire clock range of the cards, staying in the official normal/boost range.

Whereas Vray is using Boost Load Clock (up to 2050-2100 in mine) and drops to the stock clock of 1695 Mhz every 1 min.

Why is that ?

[hermit.crab]

Do you have denoiser or lens effects activated in the scene? These operations do cause GPU usage drops since they're calculated on the CPU with V-Ray GPU.

[FranklinTre]

Okay, I feel stupid now, it's so simple ... this is exactly the problem.
Both Denoizer and Lens are causing this thing, seperatly.

Thanks for the answer.

Something I never understood completely. Is it possible to render a frame, and then calculate accuratly Lens Effect and denoizer ? Even thow I'm not sure this phenomenon is a problem for redering time, can't tell.

[hermit.crab]

Setting the Image Sampler as Bucket (Render settings>V-Ray>Image Sampler) would do exactly that - it would render out the image and afterward apply the effects. Regarding the rendering time, that depends since the progressive image sampler is used for scenarios where you wish to have control over the rendering process. By that I mean, the ability to stop the rendering depending on the desired quality and according to the time limitation.

[FranklinTre]

That is exactly why I use progressive sampler all the time.

Well, I suppose I need to live with this !

[hermit.crab]

Another thing you can do is set the Post Effects rate (Render settings>Settings>System), which controls the frequency of post-effects updates, to 0. Zero disables updates during progressive rendering.