3090ti GPU is not running at 100% during V-Ray GPU rendering

[FilippObada]

Hello guys! I have an issue. When trying to render with V-Ray GPU (6.2) it does not use the GPU almost at all. Its rendering but very slowly, at the CPU level although the CPU is also not being used almost. The gpu (3090 ti) is running at about 10%. Its somehow rendering, but very slowly. In Vantage for example it work great. It uses 100% and its super fast.
Any thoughts on what could it be? I have the latest drivers from nvidia, but the previous one the problem was the same (this is why I updated). I even tried a very old driver, the 400...something, then the 516 and now the 561. No luck.

[FilippObada]

It seems like the problem is the task manager that is not showing correctly. In the GPU-Z it shows a load of 100%. Any way, I find it a bit strange because in Vantage it shows 100% usage in the task manager, and about the speed...better to not say anything. If its working normally and this is it for the V-Ray GPU, then Im quite disappointed. I expected better from a 3090ti even knowing the Vray GPU will be much slower than Vantage, but not that slower.
Im considering switching back to V-Ray from Vantage because of the VFB compositing and cryptomate abilities. They are super powerful but maaaan, after Vantage rendering with V-Ray feels like 2005 again.

[Muhammed_Hamed]

It seems like the problem is the task manager that is not showing correctly. In the GPU-Z it shows a load of 100%

Hi and welcome to the forums,
Task manager is not reliable for V-Ray GPU or CUDA compute tasks, it might work with Vantage(different type of compute in Windows monitoring) but not for V-Ray GPU. If you have 2 GPUs, the task manager will be useless for Vantage as well as V-Ray GPU
I have articles about monitoring the GPU resources here

and about the speed...better to not say anything. If its working normally and this is it for the V-Ray GPU, then Im quite disappointed. I expected better from a 3090ti even knowing the Vray GPU will be much slower than Vantage, but not that slower

V-Ray GPU is able to do ray-traced motion blur and expensive shading features like Random-Walk SSS, as well as complex shading graphs
The 2 products don't necessarily compete with each other, they could be used in the same pipeline for different needs.
Is there a chance you could upload me your scene for profiling the performance?
I will see if it could be faster with V-Ray GPU, and if there is something that slows it down

Best,
Muhammed

[FilippObada]

Dear Muhammed,

Thank you so much for your reply. I will upload the scene Im talking about tomorrow as Im not at home right now.

The 2 products don't necessarily compete with each other, they could be used in the same pipeline for different needs.

How would you recommend to manage that workflow in order to make the most out of it. Im asking because the image from Vantage is not the same as the image from V-Ray. Even V-Ray CPU differs from GPU, so changing between render engines is not viable for me because I do a lot of fine tuning in 3D, so when I try to migrate from Vantage to V-Ray there is a lot of work to make the image look the same (more or less) again. For example, I have now a project of 14 images that I did in Vantage. The images are at their final stage, so I would be happy to open them in V-Ray now in order to take advantage of the VFB post capabilities, but when I open a scene in V-Ray and try to render it looks very different and the work it would take to adjust the materials, light and tone mapping is not worth the gains. That being said, I love Vantage, but I also love VFB. Do you have any recommendation on how I could integrate both in my workflow? Because for now, If I start an image in V-Ray I finish in V-Ray, and if I start in Vantage I do everything in Vantage till the end.

[Muhammed_Hamed]

Because for now, If I start an image in V-Ray I finish in V-Ray, and if I start in Vantage I do everything in Vantage till the end.

They are different engines and will produce different outputs, having the flexibility to choose the renderer at the start of the project could be handy
In addition, you can take the EXRs from Vantage and load in the VFB to use V-Ray's post processing, in the Frame buffer click on File, Open, you will be able to load EXR files.

Some of our clients use Vantage to render camera animations very fast or turntables for some assets. Others will use Vantage to setup camera composition in 3D space, then bring all the cameras back to V-Ray/V-Ray GPU
Vantage excels at large-scale exteriors, where you have many instances for trees, vegetation and buildings. V-Ray and V-Ray GPU are slower to process a lot of triangles, the workflow becomes quite slow.
V-Ray and V-Ray GPU are able to render ray-traced motion blur and expensive shading effects like SSS and skin

Best,
Muhammed