Vray 3.6 - GPU + CPU

V-Ray already has a very robust distributed rendering system, it can use hundreds of nodes to contribute to a render without much overhead.
In the GPU+CPU mode, it use the GPU render engine and has the CPU execute CUDA code to act another nVidia GPU.
I did a simple test:
GPU only : 1m43.3s
GPU+CPU : 1m5.3s
about 37% faster if I have the math right.


And so your GPU is hot running, if you don’t use a GPU monitor, so you can hear the fans running?

I used the nVidia tool “NvGpuUtilization” and it was at 100% most of the time

Sounds good. Thank you.

Here is my test I made in Vray 3.4 for SketchUp. I think in Rhino3d it should be similar.



I wonder if it’s still valid in v3.6.

I will make test with pictures tomorrow. But in my opinion 3.6 is faster and there is no difference in brightness with different settings. Picture from CPU and GPU looks the same.

And here are images with time stamps.

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cool model, is this available to download or buy ?

roju, what CPU and GFX do you use?

Thanks a bunch

Here I tried to maintain the same noise level/image quality, but GPU+CPU could be a bit less noisy and the denoiser less aggressive, but it shows the value of these settings:

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ok thanks for all your input although my original question still stands!

What situation would you ever just render with CPU? Or just GPU?

Surely you want the render done as fast as possible which will ALWAYS be CPU & GPU together…

It depends first on your hardware. With a weak GPU you’re better just using the CPU.
Do a simple test like the one I’ll post below to decide for yourself.

Another method to do the testing; render for a defined amount of time. Here I asked to render for one minute (click on the image, there’s 5 cars):

Some observations:
-Not all materials clean up faster with GPU
-The Denoiser has some better data to work with from the GPU renderer, the result is less splotchy
-The weakest setting of the denoiser is still strong, I’ll test with custom settings with lower values
-For one minute, these are all pretty incredible results!

In 3.4 there was a difference in how reflections and some materials were represented when using CPU only or with GPU acceleration - depending on the render settings.

3.6 is much better, there still appears some cases where the GPU engine doesn’t quite work as well as the CPU:

i7 4790K, GTX 980 Ti

here is my model https://drive.google.com/open?id=1RZ9bjagv_5UtXTK1w7qcdCFumDiiKfbm

(without trees from CGAxis, and furniture from Herman Miller which You can download here https://www.hermanmiller.com/design-resources/3d-models-revit/3d-models-by-product/tables.html)

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Thanks Robert, very kind…

what file type do you generally use to download furniture?

There is a very good post by Chaos Group explaining the difference between the different types of rendering engine of V-Ray: https://www.chaosgroup.com/blog/understanding-v-ray-hybrid-rendering

The article explains the advantages and disadvantages of using Hybrid Render

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can I ask how you get so much light inside the building…? I am struggling with my lighting setup to replicate your lovely render…