making cpu scene render with gpu rendering

[Muhammed_Hamed]

Hey Witt3D and thanks for the feedback, I will comment on some of the points below

Not that much info about GPU rendering, on this forum and even on the internet, at least not very delighting one.

We are in the process of updating our GPU documentation, there will be a section about this topic soon.

but we find out not a fair comparision the one you are just showing up.

· RTX 3090 cost around 2.500 euro, but 5950X just 500 euro. A better comparision should be RTX 3090 with Amd Ryzen 3970X.

I tested on a Threadripper 3970X as you requested, here are the results

Clay test,
V-Ray Bucket mode, 3970X CPU 32 cores/16 threads >> 28 Minutes 2 Seconds
V-Ray GPU Progressive mode, RTX 3090 >> 3 Minutes 17 Seconds

Beauty test,
V-Ray Bucket mode, 3970X CPU 32 cores/16 threads >> 33 Minutes 48 Seconds
V-Ray GPU Progressive mode, RTX 3090 >> 10 Minutes 4 Seconds

So, the same conclusions from above are correct. a 3090 is much faster than a Threadripper 3970X or even the 3990X which is +4000 Euros

One note is that a 3090 is 1800 Euros here, and prices are going down everywhere. In some places it is even closer to MSRP
A 5950X is 850 Euros here, I have never seen it near 500 Euros..
On the other hand a 3970X is out of stock in most places now. You will only find the 3975WX Pro which is similar in performance but more expensive, it is +3000 Euros here

A second note is that a Threadripper requires quad channel memory, expensive cooling and expensive board, this all adds up to the cost

A third note, you can only house a single Threadripper CPU per machine, while it is possible to use multiple RTX GPUs in the same system. Up to 4 per machine without issues, and expandable to 7 with Riser cables. This expandability is one big pro on the GPU side

Anyways, I used this CPU in my testing above because it is a consumer board which is accessible to most people.. it doesn't require an expensive board or cooling.

· We can accept the point of view with the noise thresold, but both has to been render with the same method, progressive method consumes more memory and has some limitations, so it is also an unfair comparision.

This is not correct, progressive mode is very reliable on GPU and it is the recommended way of working. It is faster than Bucket mode in most cases, and uses less GPU memory.
Keep in mind that V-Ray and V-Ray GPU are different render engines, they produce different noise results. The GPU engine was written from scratch to be as fast as possible and to unleash the GPU hardware.
The GPU engine will have a brighter and cleaner result, you can get away using a higher noise threshold in many cases.

The first point would be to compare with the same method (progressive or bucket) and with two equal price piece of hardware, GPU and CPU. This can give us a good starting point to know, where ever we have to spend more money pon GPU or CPU to get speed improve. We havent find nothing close to this on the internet. And it all about money. Where we should put all our budget in.

I worked as a concept designer/visualizer in Print for more than 6 years. I transitioned my previous 2 studios Renntech and Carlex into GPU rendering fully, and both are still stuck to GPU rendering until now. I did a lot of research on this topic, and eventually convinced the team leads into making the transition. I have production experience with many renderers including V-Ray, Octane, Redshift, Arnold and others, I have seen it all
I joined Chaos last September as a GPU product specialist, we do performance testing regularly between V-Ray and V-Ray GPU.

but do we have a good criteria to know if we can render our scenes with GPU?, or do we have to spend thousands of euros on a workstation with the latest Graphic cards, and after that hit render and get memory exception error?
Some of our questions are regarding this matter. And it would be greatful that someone in Chaosgroup put some info on this.

System memory and GPU memory don't work in the same way. Some of my scenes that take 70-80 GB of system memory would render fine on 11 GB GPUs
V-Ray GPU is quite efficient on using GPU memory, if you send me a sample scene I can test and show you the memory footprint between CPU and GPU. I have dual 3090s NVlinked, I think 48 GB of GPU memory are going to work in your case.

Another note is that V-Ray GPU and other GPU renderers will use a lot of system memory, this is normal. You ideally need 128 GB of system memory for a dual-3090 setup

We have read a lot about this matter, and we have come close to confirm that some Nvidia cards with NVlink can share their VRAM memory. It seems, but havent get an official reply, that Vray 5 is ready to handle it. Is it so?

Yes V-Ray GPU supports NVlink and memory pooling, this applies to version 5 and version 4

How much Vram do we need, when we need 120 GB for CPU? More or less, nothing like, it depends on bla,bla,bla,... . Just a rough value. So we come close to know how many graphic cards do we have to link with Nvlink.

At least dual 3090s + NVlink to be safe
You could send me a sample scene and I will show you the numbers

Vray is compiled to work with the Ram memory of the computer, even if it slows a bit the render, or you just cannot render the image?

This is not supported yet, it will come in a future update. We call it OOC Geometry/Textures, where V-Ray GPU will use system memory when it runs out of GPU memory

if i have n AMD Ryzen 3990X with 256 GB RAM i can render whatever i want, pretty sure aobut this. It can take a night long, but i can render it on high resolution image. Is it the same with GPU? Or we get a point where we have spend 8.000 euro on a workstation and we hit render and get an error and no final render?

a 3990X + 256 GB of memory will cost you 7000 Euros at least, it is not a cheap setup.
On another note, V-Ray GPU is quite reliable now, you will be safe as long as you start your projects from scratch using the GPU engine. It is being used in production in many studios, Porsche, Dabarti and others

Best,
Muhammed

[Witt3D]

I tested on a Threadripper 3970X as you requested, here are the results

Clay test,
V-Ray Bucket mode, 3970X CPU 32 cores/16 threads >> 28 Minutes 2 Seconds
V-Ray GPU Progressive mode, RTX 3090 >> 3 Minutes 17 Seconds

Beauty test,
V-Ray Bucket mode, 3970X CPU 32 cores/16 threads >> 33 Minutes 48 Seconds
V-Ray GPU Progressive mode, RTX 3090 >> 10 Minutes 4 Seconds

Hi Muhammed, thank you for the new test. Good to know this values.

This expandability is one big pro on the GPU side

We have read somewhere that some graphic cards can just be link on pairs with Nvlink, it means that you just can put 2 together. I dont know if that is so with 3090 or not, just can you confirm that you can put more than 2 3090 together? Thank you.

This is not correct, progressive mode is very reliable on GPU and it is the recommended way of working. It is faster than Bucket mode in most cases, and uses less GPU memory.
Keep in mind that V-Ray and V-Ray GPU are different render engines, they produce different noise results. The GPU engine was written from scratch to be as fast as possible and to unleash the GPU hardware.
The GPU engine will have a brighter and cleaner result, you can get away using a higher noise threshold in many cases.

Ok, still for us an unfair comparasion. Not same rendersettings, not same render engine, you told is rewritten from scratch, not same limitations on each render engine, so for us is simply not a fair comparasion. True ones have to be done under exact same conditions and with the exact same result, not slightly different, but anyway we cannot see any on the internet cause we guess that GPU and CUDA under Bucket mode will be slower than CPU.

I worked as a concept designer/visualizer in Print for more than 6 years. I transitioned my previous 2 studios Renntech and Carlex into GPU rendering fully, and both are still stuck to GPU rendering until now. I did a lot of research on this topic, and eventually convinced the team leads into making the transition. I have production experience with many renderers including V-Ray, Octane, Redshift, Arnold and others, I have seen it all
I joined Chaos last September as a GPU product specialist, we do performance testing regularly between V-Ray and V-Ray GPU.

Thank you, we appreciate your experince and means a lot for us to take the right decision.

System memory and GPU memory don't work in the same way. Some of my scenes that take 70-80 GB of system memory would render fine on 11 GB GPUs
V-Ray GPU is quite efficient on using GPU memory, if you send me a sample scene I can test and show you the memory footprint between CPU and GPU. I have dual 3090s NVlinked, I think 48 GB of GPU memory are going to work in your case.

GReat to hear that!!!

At least dual 3090s + NVlink to be safe
You could send me a sample scene and I will show you the numbers

WOW, that would be awsome!! Should be send a vrscene file, the point is that some textures would not be accessible, cause inside our scene there are lots of small vrscenes files with their own textures paths.

This is not supported yet, it will come in a future update. We call it OOC Geometry/Textures, where V-Ray GPU will use system memory when it runs out of GPU memory

Again that is superb!!! REally good news on that, and should make it easier to change to GPU.

Thank you again for all the info. So it will be easier to take the right decision.
Best.

[Witt3D]

And sorry, you just tell us where to buy to get your list of prices. Would be great. Here is what we get:

Ryzen 5950 for 556 euros.
https://www.google.es/shopping/product/1241695243945151256?q=5950X+ryzen&client=safari&hl =es-es&biw=414&bih=719&tbs=vw:l&prmd=snvi&prds=eto:37 7 8454643158039002_0,cdl:1,prmr:1,rsk:PC_13904683267 290411097,cs:1


RTX 3090 nothing less than 2100 euro
https://www.amazon.es/rtx-3090/s?k=rtx+3090

a 3990X + 256 GB of memory will cost you 7000 Euros at least, it is not a cheap setup.

Seriously, we have two different budgets here for two different workstations with 2 rtx 3090. Any of them is less than 7.000 euros. And again, for production i can guarantee with the above setup you can render anything you want. With GPU system right now you cannot confirm that.

As mentioned before, for us would be lovely, great, awsome, incredible to move on a system where we have to spend less money and get much faster render times. WOW, this is magical and our dream.
The point is to know in a certain way that you can move your porduction to GPU without any great problem. As told you before, should be really painful and inadmissible to spend 6.000, 5.000, 7.000 euros on a GPU Workstation and after that be impossible to render some scenes. With the other config that wont happen at all.

[digitarch]

Hi again,

after another round of testing, everything works fine with simple scenes. But if I try to use GPU on a normal work project it crashes, does not render at all or renders black.
Cleaning up the scene helps a bit, but I still cannot render a complex scene with GPU. Especially Itoo Forest objects and Vray proxies (foliage) seem to bring GPU to its limits.

What is the best method to set up a more complex scene with GPU rendering?

We are still testing with the GeForce RTX 3060 with 12 GB

Best regards.

[luisgamino2]

***********

[Muhammed_Hamed]

luisgamino2 I haven't gotten a chance to reply to your other threads yet. I have been very busy recently with the new Beta
Keep in mind that the experience in V-Ray for SketchUp is very different than V-Ray for 3Ds Max. There is a new version in Beta now for 3Ds Max, it will be available for SketchUp soon
I edited your reply for now until I get a chance to comment on what you wrote, then will edit it back to what you wrote
Many of the points you mentioned are addressed in the new Beta, plus you don't follow my advice on using progressive mode/Cuda mode for best memory efficiency. I will write about it in details tomorrow

Thanks!

[Muhammed_Hamed]

Hi digitarch

Hi again,

after another round of testing, everything works fine with simple scenes. But if I try to use GPU on a normal work project it crashes, does not render at all or renders black.
Cleaning up the scene helps a bit, but I still cannot render a complex scene with GPU. Especially Itoo Forest objects and Vray proxies (foliage) seem to bring GPU to its limits.

Does it crash out of memory? could you please screenshot me the log
If it is not a memory crash, I will need the scene. Being able to reproduce the crash on our side, I will make sure this gets fixed

What is the best method to set up a more complex scene with GPU rendering?

>> You should be careful with Displacement using screen space, it is one reason people run into GPU memory limitations. We are aware of this, will take a look at GPU displacement whenever comes a chance, it is high priority on the development roadmap.

>> Stick to Progressive mode, could also stick to Cuda engine which uses less GPU memory than RTX. This is part of the current development effort for V6, to have better memory management.

I would love to help, any crashes that I produce on my side, I will make sure it gets fixed.
On another note, V-Ray 6 makes comparing performance a much easier task. The GPU UI will translates sampling settings from V-Ray to V-Ray GPU under the hood. We also updated the sampling defaults for V-Ray GPU and the underlying formula for calculating samples. Some of the changes are currently in Beta 2, and more will come at the official release

Best,
Muhammed