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Simple: CPU and RAM make no difference in DAZ.

elhectroelhectro Posts: 62
edited August 2023 in Daz Studio Discussion

Hi. Just want to write this post that may help new users who are considering upgradiing their PC.

As I got a good business in VN, and I began rendering about 500 images per month, I upgraded my PCs at the beginning of the year.

I went for a great ASUS with i9 12th gen CPU, 16gb RAM and a 3070ti GPU, 8 Gb VRAM (Gpu's memory). I wrongly believed having the fastest CPU would be significant for Daz performance. Comparing to my old lap and pc this was like a spaceship. Renderings that took 3 minutes now were 15 seconds, as my old PC from 2017 had only 2 gb of VRAM.But then, I realized when the scene was too big, the laptop didn't use the GPU for rendering and was almost as slow as my old PC's. In the rendering process, the RAM usage escalated from 70 to 90%, then I believed it was a RAM issue. I upgraded the RAM to 40, and no changes.

In the meantime, I got a desktop with a 3060 12 Gb VRAM and a modest i5 10th gen CPU, and 16gb ram. This desktop has better performance than the lap with lower RAM (16 vs 40 Gb), slower CPU (i5 10th gen vs i9 12th gen), 3060 vs 3070ti GPU, but with 12 Gb VRAM vs 8 gb VRAM. Because of this extra 4GB in VRAM, it always renders the big scenes in GPU, and the iray preview runs faster.

So, the conclusion VRAM is THE MOST IMPORTANT COMPONENT that will improve Daz performance. I'm sure this not new 3060 with 12 Gb VRAM will outperform the brand new 4060ti with 8Gb.

Post edited by elhectro on

Comments

  • Richard HaseltineRichard Haseltine Posts: 100,765

    Having enough RAM on the GPU is crucial, but as long as you do the GPU performance will show clearly - so your 4060 should beat the 3060 when the scene fits into its memory. But certainly performance is secondary to having sufficient VRAM.

  • PerttiAPerttiA Posts: 10,024

    16GB's of RAM is just not enough, one should have 3 times more RAM than VRAM or at least 32GB's.

  • elhectroelhectro Posts: 62
    edited August 2023

    PerttiA said:

    16GB's of RAM is just not enough, one should have 3 times more RAM than VRAM or at least 32GB's.

    No, that's not true, at least in my experience. I upgraded to 40Gb of RAM and Daz works exactly the same as with 16Gb. It still renders big scenes with CPU and can't use the GPU. It doesn't matter that my RAM is 5 times bigger than the GPU RAM. You can have 128 Gb of RAM but if your GPU is still 8 Gb, it will never surpass a 12 Gb CPU with 16 Gb RAM.

    Post edited by elhectro on
  • GordigGordig Posts: 10,049

    elhectro said:

    PerttiA said:

    16GB's of RAM is just not enough, one should have 3 times more RAM than VRAM or at least 32GB's.

    No, that's not true, at least in my experience. I upgraded to 40Gb of RAM and Daz works exactly the same as with 16Gb. It still renders big scenes with CPU and can't use the GPU. It doesn't matter that my RAM is 5 times bigger than the GPU RAM. You can have 128 Gb of RAM but if your GPU is still 8 Gb, it will never surpass a 12 Gb CPU with 16 Gb RAM.

    It feels like you're drawing somewhat the wrong conclusions from this. VRAM determines whether the GPU will be used to render at all, but that doesn't mean that system RAM and CPU performance are irrelevant. If you had an A6000 with 48GB of VRAM but still only 16GB of RAM in your system, you'd see that RAM is far from irrelevant.

  • Richard HaseltineRichard Haseltine Posts: 100,765

    Gordig said:

    elhectro said:

    PerttiA said:

    16GB's of RAM is just not enough, one should have 3 times more RAM than VRAM or at least 32GB's.

    No, that's not true, at least in my experience. I upgraded to 40Gb of RAM and Daz works exactly the same as with 16Gb. It still renders big scenes with CPU and can't use the GPU. It doesn't matter that my RAM is 5 times bigger than the GPU RAM. You can have 128 Gb of RAM but if your GPU is still 8 Gb, it will never surpass a 12 Gb CPU with 16 Gb RAM.

    It feels like you're drawing somewhat the wrong conclusions from this. VRAM determines whether the GPU will be used to render at all, but that doesn't mean that system RAM and CPU performance are irrelevant. If you had an A6000 with 48GB of VRAM but still only 16GB of RAM in your system, you'd see that RAM is far from irrelevant.

    The point is that Daz Studio needs to prepare the data to be sent to Iray - so it needs as much space as the render data will take, plus enough space for the scene data (which may be very different from the render data - usually the scene will have things like joint and shape modifiers, while the render gets just the final shape, but the scene will use lower resolution maps and geometry by default - plus space to process the differences.

  • elhectroelhectro Posts: 62

    Gordig said:

    It feels like you're drawing somewhat the wrong conclusions from this. VRAM determines whether the GPU will be used to render at all, but that doesn't mean that system RAM and CPU performance are irrelevant. If you had an A6000 with 48GB of VRAM but still only 16GB of RAM in your system, you'd see that RAM is far from irrelevant.

    I don't know what happens if you get a super Gpu with 48 VRAM. But what you can't deny is that if you have 8Gb of VRAM, upgrading RAM and CPU are irrelevant comparing to upgrading the GPU to 12 Gb VRAM. And this info is really useful for people who are looking for upgrading their PC and don't have a fortune to get a 48 Gb GPU.

  • PerttiAPerttiA Posts: 10,024

    elhectro said:

    Gordig said:

    It feels like you're drawing somewhat the wrong conclusions from this. VRAM determines whether the GPU will be used to render at all, but that doesn't mean that system RAM and CPU performance are irrelevant. If you had an A6000 with 48GB of VRAM but still only 16GB of RAM in your system, you'd see that RAM is far from irrelevant.

    I don't know what happens if you get a super Gpu with 48 VRAM. But what you can't deny is that if you have 8Gb of VRAM, upgrading RAM and CPU are irrelevant comparing to upgrading the GPU to 12 Gb VRAM. And this info is really useful for people who are looking for upgrading their PC and don't have a fortune to get a 48 Gb GPU.

    Plenty of posts, where someone with 8-16GB's of RAM is struggling to keep their computers from crashing as there are problems with how their virtual memory is set up. Adding a GPU with more VRAM and adding RAM go hand in hand.
    One does not get the benefit from more VRAM if RAM is not increased at the same time and vice versa (when talking about Iray rendering in DS)

  • vectorinusvectorinus Posts: 120
    edited August 2023

    PerttiA said: "...Adding a GPU with more VRAM and adding RAM go hand in hand. One does not get the benefit from more VRAM if RAM is not increased at the same time and vice versa..."

    Golden words. Imagine that the GPU accelerator is a powerful racing car, and the RAM is the autobahn. Try to accelerate your beautiful car on a very short road to its maximum speed. Don't forget the brakes. You will need them at the end of the too short path.

    Post edited by vectorinus on
  • TimberWolfTimberWolf Posts: 288

    Elhectro,

    We have two super GPUs with 48GB of VRAM. Our (commercial) rendering machine is fitted with 128GB of system RAM. iRay uses system RAM to process the scene data before it's fired to the GPU so think of it like a compiler for a programming language. The process takes a lot of intermediate steps to come up with the solution and that process takes far more memory space than the final result. Like the solution to a mathematics problem - the working out takes a lot of space. The final answer, not so much. This is why, as many other people have said, you can't just throw a better GPU into your system without considering your system RAM. If the calculations for this scene exceed your system RAM the very best result you will get is that the whole thing slows to a crawl as your system page faults and starts swapping data in and out of RAM from your disk. Most people find Studio just crashes.

    Where I do agree with you is that there has been a lot of threads recently about hardware upgrades involving considerable expense that will have an absolutely negligible effect on rendering speeds. Faster RAM, PCI busses, a 0.2 GHz CPU speed increase. It's their money but it won't help. GPU upgrades are the most cost effective improvement but you do have to bear in mind the working space (system RAM) they need.

     

  • vectorinusvectorinus Posts: 120
    Yes. Dramatic post. But in fact, there are several ways to get around these troubles. These methods have been around for a long time. It is possible to render the scene in parts: first render the environment and set it as a background, and hide the environment itself. Then render the characters - all or individually. Since all the objects is rendered in PNG format with transparency, it will be easy to flatten the images in any 2D editor and do any post-processing. Paint on the shadows, add a blur around the edges, increase the contrast. Lightly paint on the eyes of the ladies and hard folds on the men... After a while, the masterpiece is ready. And your rested 3D accelerator will thank you ;-)
  • GordigGordig Posts: 10,049

    elhectro said:

    Gordig said:

    It feels like you're drawing somewhat the wrong conclusions from this. VRAM determines whether the GPU will be used to render at all, but that doesn't mean that system RAM and CPU performance are irrelevant. If you had an A6000 with 48GB of VRAM but still only 16GB of RAM in your system, you'd see that RAM is far from irrelevant.

    I don't know what happens if you get a super Gpu with 48 VRAM. But what you can't deny is that if you have 8Gb of VRAM, upgrading RAM and CPU are irrelevant comparing to upgrading the GPU to 12 Gb VRAM. And this info is really useful for people who are looking for upgrading their PC and don't have a fortune to get a 48 Gb GPU.

    The fact that VRAM determines whether a render will use a GPU is common knowledge on these forums, and is information that anyone asking about GPUs around here will receive. I'm not trying to deny that. You're still wrong to say that CPU and RAM are irrelevant, because they're not.

  • DartanbeckDartanbeck Posts: 21,551
    edited August 2023

    Using Iray or not, if we want to work on some huge project it's our system that takes the weight.

    Post edited by Dartanbeck on
  • elhectroelhectro Posts: 62
    edited August 2023
     

    The fact that VRAM determines whether a render will use a GPU is common knowledge on these forums, and is information that anyone asking about GPUs around here will receive. I'm not trying to deny that. You're still wrong to say that CPU and RAM are irrelevant, because they're not.

    Then explain to me why the i5 with 16 Gb RAM but with a 3060 VRAM 12Gb, outperforms in everyway an i9 with 40 Gb RAM 3070ti with 8 Gb VRAM.

    Post edited by elhectro on
  • vectorinusvectorinus Posts: 120
    Probably the whole scene fits in 12 gigabytes of the 3060 card, and does not fit in the 8 gigabytes of the 3070. Any graphics card starts to slow down a lot if it cannot contain the render data completely. In competition with a card that can hold data completely, the RAM size won't help the 3070 card. Have you tried rendering big enough scenes on both systems?
  • Richard HaseltineRichard Haseltine Posts: 100,765

    elhectro said:

     

    The fact that VRAM determines whether a render will use a GPU is common knowledge on these forums, and is information that anyone asking about GPUs around here will receive. I'm not trying to deny that. You're still wrong to say that CPU and RAM are irrelevant, because they're not.

    Then explain to me why the i5 with 16 Gb RAM but with a 3060 VRAM 12Gb, outperforms in everyway an i9 with 40 Gb RAM 3070ti with 8 Gb VRAM.

    How much system memory on the first system? If you are getting the better performance with 8GB or 16GB then that would be a turn up for the books, but if you hve 32GB or more then that would be pretty much expected (though there would probably be scenes which the GPU can handle but the system can't prepare, or can't prepare without an enormous slow down). No one is saying that a good GPU isn't crucial, just that it does need a certain amount of "infrastructure" in the rest of the system to see that improvement.

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