New to vray (coming from octane) I am evaluating if it is better to invest in GPU rendering or CPU rendering moving forward. Quick tests give me the impression that a lot of features are not supported on GPU and it actually looks like a completely different renderer (looks worse!) And it crashes a lot making it seem like a something to avoid. Also ipr is a lot faster to first pixel on CPU. So I guess I am asking those more experienced in vray if GPU is viable in a production setting.
No really simple answer unfortunately.
You’re correct, they are entirely different renderers. Choose with care:smile:. There are many, many threads here discussing the issues/benefits and supporting both use-cases, with many people solely using GPU with great success,
albeit I would guarantee with unavoidable workarounds/extra CPU passes for that which does not now and may never work with GPU, due to either physical or technical limitations.
Also, depending on the size of your scene and textures, you may not even be able to fit it on your card, which is of course not an issue with CPU.
​​​​​​​It’s definitely worthwhile scouring the forums for any other posts you can find.
Hello @filip_wnstrm and welcome to the forum
I’ve been using the GPU engine in Vray since 2016 or so, I have used it extensively in production during my time in Carlex and Renntech. It helped us massively and was able to deliver
while it doesn’t exactly match the CPU renderer in all features the GPU engine has evolved throughout the years, specially version 5 with features like Native ACES support, GPU Light Cache, New Sky model, Stochasitc texture tiling, LightMix and core features like NVlink support and RTX acceleration
Some examples from the community
There are many that rely on the GPU engine almost exclusively in production, myself included
Quick tests give me the impression that a lot of features are not supported on GPU
The GPU workflow might be different for specific tasks like material or object IDs for example, same for interactive rendering and bunch of other things., I recommend starting with this page and the FAQ page
And if you have questions on specific parts of the GPU workflow feel free to post in the GPU section, I would love to help 
it actually looks like a completely different renderer (looks worse!)
It is a different engine yes, you are not going to get the exact same results as the CPU engine. Feel free to reach out if you wanna achieve a certain look you get on CPU
And it crashes a lot making it seem like a something to avoid
You need to be on the certified Nvidia driver 471.11 you will find it in the GPU page here
I recommend using the latest stable nightlies for 3Ds max or Maya, they have been stable in my experience
Also ipr is a lot faster to first pixel on CPU
it depends on your hardware, Here is a preview of the GPU IPR in Maya and 3Ds Max, on one RTX 3060 (which is the cheapest Ampere GPU in the market)
And second video is an RTX 3080
which DCC and Vray build do you use? will make a video with my interactive rendering workflow for you, it is usually very fast
I am evaluating if it is better to invest in GPU rendering or CPU rendering moving forward
I have been stuck to GPU rendering for 2 main reasons, speed and expandability
This is an example here , this was rendered in 20 minutes in 5k resolution on 2 GPUs.. 2 strong GPUs are basically a local render farm at your finger tips, that doesn’t take much space
And the setup is expandable easily to 4 GPUs, anyone can setup a 4-GPU workstation at home.. and you could even expand further to 8 and 10 GPUs per machine if you need that, there are a few places that offer such setups
I also recommend checking out Chaos Vantage which offers pure ray tracing performance on GPUs for your Vray scenes, it has its own place in my workflow next to Vray GPU
This doesn’t mean GPU rendering is better than CPU rendering, I have used both throughout the years and leaned towards GPU for what I need. Either way Vray does both very well and even if you have a good CPU or if you have a local CPU farm, you could use all of that power in Vray GPU through Hybrid rendering
Hope this is gonna be helpful with your investment plans, feel free to tag me if you have more questions about the GPU workflow
Best,
Muhammed
@Muhammed_Hamed , Wow, what an extensive answer, thanks! I personally use mainly Houdini (18.5.596) on Ubuntu Linux 20.04 LTS with Nvidia 465 series drivers but will upgrade to 470 series now for the further tests. Current workstation is an old x99 5820 but with a RTX 3090 GPU. Also have a 2080 ti that I cannot install since the PSU dies and it has been hard to find new ones available. Anyway, I come to VRAY with beginner eyes (Most experience using Redshift and Octane before) and am very surprised that the GPU and CPU modes are actually not really compatible. Would be great to dev/ipr on CPU and then turn to GPU for rendering. Even with this old CPU I get a good preview within 20 S while the GPU takes about a minute until I see anything I can make decisions from. This is with realistic arch interiors that I have been provided by exporting scenes as .vrscene from 3DS.(My collaborator that uses 3DS + VRAY CPU and have not adapted it for GPU.) CUDA mode was somewhat ok but many materials looked very bad. RTX mode almost always crashed or locked my computer. I will test again with newer drivers. Initilly I was thinking in getting a server with 4xRTX a5000 on a TR Pro platform but the instability got me thinking that maybe a few regular TR 3990x with no GPUs would be a more reliable rendering system. Focus will be on realistic interiors mostly.
GPU seems as stable as CPU for me. 3dsmax interior/archviz scenes on 1070+3090. lack of features should not bother you if you are used to redshift/octane. I haven’t try 3dsmax CPU >> vrscene >> houdini GPU export but if I was to guess - this will not be smooth.
one thing to consider - if your psu does not handle 3090 + 2080 it is possible that it has trouble with power consumption spikes of 3090.
All components has been written from scratch and optimized for the GPU code, this includes materials, shaders…etc hence they will produce slightly different results, which is expected. You will need to decide at the start of your project and pick which engine you use, swapping mid project is not gonna be ideal
The GPU IPR is much faster than CPU IPR for me even though I have a 5950X (triple the performance of your CPU) and I only use one single GPU (RTX 3060)
Keep in mind that the first run after installing a GPU driver or a new Vray build, this first run will be slower as it will compile the kernel for GPU rendering.. which takes like 1-2 minutes alone, this happens only once then the following runs should be very fast
And there are some controls you can use to speed up the GPU IPR,
-Enable “export View continousely”
-Enable the AI denoiser and set update frequency to something like 50 (higher means more updates for densoier and lens effects, lower means fewer updates and 0 means the denoiser only updates when you stop the IPR)
-Disable Auto setting in the IPR tab, use undersampling of 1 and rays per pixel of 1
I recorded a video here using Houdini 18.5.633 and Studio driver 471.11
These scenes are setup for the CPU engine, issues come mostly because of translucency which is not supported on GPU (coming soon to Vray GPU)
You will need to tweak some of the shaders to make it look right, I will upload something you can test with shortly
In this situation, even using 4x 3060s is gonna take less space and will be less expensive than multiple Threadripper machines .. In my testing this single RTX 3060 is as fast as a 3970X
I recommend updating to new drivers, and giving yourself more time to test. If you are gonna work the shading from scratch in VFH for your interiors, GPU rendering is a very solid option
And about PSU, you will need 800 Watts or so for these 2 GPUs.. A second GPU is gonna be handy even just for viewport and windows performance
Best,
Muhammed
@Muhammed_Hamed .Thanks for lot’s of valuable info! I will have to investigate further then. It’s just when you quickly read the marketing on chaos web you might expect that it is interchangeable GPU<->CPU. Maybe they could have been clearer with this calling them by different names. Btw, How did you get VRAY to work on 18.5.633 ? I can only find installer up to .596
the GPU engine runs fine on CPU and gives the same results(Hybrid rendering), but not the other way around. I get your confusion, it is usually not the easiest thing to explain
You need to send an Email to support requesting access to the nightly builds, you will find them at Chaos
Usually you wanna use the latest nightly build for VFH
I’m glad this was helpful, if you have questions feel free to tag me
I have been using vray for over 12 years now (as owner of an arch vis studio and then again in retail / product /fashion work) and have only swicthed to Vray GPU in the last year and I will say while it is def faster over all its still very very bad in terms of feature parity and stablity. I have found 6 bugs in the last 12 weeks alone that ended up with me going back to CPU.
I have so much stuff set up around Vray its difficult to move away at this point but im getting very close. Vray GPU has been bascially abandoned by Chaos, there are never any improvements, bugs are never fixed they will just ask you to endlessly spend time submitting broken files and then ignoring these. Support staff will pop up and just say please submit file - but no I dont have time, why are we even paying for this when its getting live tested on its customer base. What has happened is that is was bundled with CPU but never ever finished and is still experimental. I think it needs to be split off and made good - or just cut it off. Its beyond the joke now - ask around youn will get the same answers.
If you need reliable GPU rendering i would recommend Redshift or stick with Vray CPU (which is very good still) and invest in more CPUs *i wish i did this vs getting 10 x 3090s*
avoid vray gpu while you can its not worth the pain!
it’s all about perspective - there are definitely hurdles to be expected coming from VRay to VRay GPU. but I would be quite interested in hearing from people with experience in other GPU engines switching to VRay GPU. it would at least be apples to apples comparison.
We tried to make the switch back a couple years back and had some good success. However constantly figuring out workarounds for incompatible features between CPU and GPU, as well as limitations with plugins like Forest Pack led us to going back to Vray CPU and Corona. The speed comparisons were just not that significant compared to the headaches we would have working with GPU in its current state.
Lastly the gpu mark up/ shortage is also making it even harder to jump in and upgrade to the latest hardware.
For reference our main workstations are Threadrippers 1950x and 2990x and we were using 4x Nvidia Titan Xp.
I do like what Chaos is doing with Vantage however, but it seems still pretty far for us to be using it in our daily workflow.
these issues have been around for over 3 years lol
so from that perspective Vray GPU is a definite failure. If you look hard enough you will find edge cases of it being useful but overall i still would recommend Vray CPU if you want to use softweare thats not live tested on its users for 3 years! i dont know anyone coming to vray gpu from redshift or octane, its all people going the other way.
In the end we had to choose CPU since to many issues and missing features on GPU.