Help: what AMD CPU for a RTX 3080?
raylikesvideos
Posts: 9
Hello, soon I will update my Setup but I have a doubt to choose the CPU. I want to have the best CPU but is it really necessary to have the best CPU to use DazStudio?
because the most important thing for DS is the GPU, right? (in my case I will buy the 3080 12GB)
The best Amd CPU is the Ryzen 5 5950x but if I buy the R5 5900x the rendering times will be similar?
I ask because the 5900x is much cheaper than the 5950X, so if I can save some money that would be nice.
Thanks
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I would rather have pure single thread performance for use in making the vieport window smoother when creating a scene.
I find the render set up time where it uses all cores to be fairly small such that the benifit of my 3900x vs my older 3600 system is negligable in the real world. I would look at Intel 12400/12600K systems or 5600x/5800x if you want to stick with AMD. The 3900x was great for CPU rendering (realitively speaking) when I was struggling to fit things in a 1080ti. But is irrelevant now with a larger memory GPU.
Perhaps DDR5 could help with load times in future Daz builds, but I hear that you can't get 4 slots working at over 4800mhz speeds, so I'd just stick with DDR4 personally.
Well, I'd would go for an AMD Ryzen 7 5700G and you get an integrated 8 core 16 thread 5nm process APU (CPU+APU on one die). Then, in the fall 2022 (hopefully) when AMD releases the next up upgrade to those APUs they are already on record (I think I remember this right) as saying it will be the new RDNA2 architecture which is hardware GPU supported ray tracing. The bonus of these APUs is they cost less then the top flight CPUs like the AMD Ryzen 9 5950X by a considerable margin. I bought my AMD Ryzen 7 5700G for less than $400 USD.
Maybe, if we are really lucky they will up the cores on their next top flight Zen Ryzen generation to 32 cores so that we can get an APU with 16 cores. The die shrink would allow it I think. I think I will have to buy a new AMD motherboard though.
How many watts is your power supply? Can it handle the load of an RTX 3080 and Ryzen 5950, 5900, etc? My RTX 3070ti/Ryzen 5800x has a 700w power supply, you might need something bigger.
If you have not purchased anything yet, you might want to consider a pre-built system. iBuyPower and Alienware make some pretty cost effective ones.
I will buy everything again. so that's not a problem.
This is just an example.
using an RTX 3080 + R5 5950x rendering a 4k image takes 20 minutes.
If I use the combination of the RTX 3080 + R5 5900x the same 4k image, how long will it take? 21 min? 30min?
I mean, my question is: the CPU has a lot of influence on the rendering times or if it only depends on the GPU.
And if there is a difference, how big is that difference?
Because I don't want to buy the most expensive CPU if the rendering times are going to be the same if I buy a cheaper CPU.
Probably for DS, the most important is the memory. Daz is mostly single threaded and will not really benefit from a powerful processor. I would rather put extra money in the memory than in processors. The gain with a CPU will be limited (say at most 10-20%) if any, while more memory will avoid crashes and can allow some renders that would be impossible otherwise. You need 3x more RAM than VRAM to properly use your GPU. With a 3080 32GB is an absolute minimum, but 48GB or 64B are probably preferred and now I have 128GB RAM, and it is really a game changer.
yeah ill build my setup with 64GB Ram + 3080 12GB. just a wanna know what CPU I should buy.
One major thing that getting a more beast CPU helped with is viewport lag. I used to get lag in viewport with anything more than one or two people in the scene. If I try to move any slider even, it would lag for a second or two, then start moving. Was major annoyance when trying to make tweaks to anything. Now I can have even 40 people in scene, and there is no lag. I had a 1600X I think, then went to a 3900X.
Ryzen 5950x prices have dropped to $600, what can you get the 5900x for?
Check out these rendering benchmarks and decide. They do not include IRay, but they give you an idea of the performance difference:
https://www.anandtech.com/show/16214/amd-zen-3-ryzen-deep-dive-review-5950x-5900x-5800x-and-5700x-tested/14
https://www.tomshardware.com/reviews/amd-ryzen-9-5950x-5900x-zen-3-review/8
Many people don't use any CPU with a higher spec. GPU.
I still get a 4-5% CPU contribution with with a RTX3060. That is probably going to disappear with 3080. With a 3090 (and higher), people actually report the CPU holding back the GPU!
The real question is do you have any other software that can use all those threads, Iray doesn't really need them.
20 minutes again, because the CPU doesn't get involved in the rendering unless you run out of video RAM or specifically configure DAZ to use CPU & GPU, which will slow down your render times.
What you're seeing isn't 'contribution', but management.
For each gpu that iray is using, you'll be using 1 core of your cpu.
1 GPU, 4 core cpu, 25% utilization.
1 gpu, 20core cpu, 5% utilization.
4 gpu, 20 core cpu, 20% utilization.
Hate to be the bearer of bad news, but core count had very little to do with your lag problems.
For the most part, the only time core count matters is in regards to rendering. This is mainly due to almost all functions in DS still being single core.
Viewport lag is, mostly, driven by your gpu. When the cpu causes a lag problem, is in relation to other functions, such as Smoothing modifiers. These are, unfortunately, still single core functions.
For sliders, that 'lag' is because of how the genesis series works.
What most people aren't aware of, is that, the morph dials don't fully load initially, when in a 0 state, but only the presentation data(what the slider looks like on screen) is loaded and a link to the full file(DSF) is created.
When you move a slider, then DS reads the rest of the file and creates the necessary links and changes the figure accordingly.
The amount of 'lag' is going to, again, be determined by single core speed, as well as, drive type, speed and interface, and the complexity of the particular morph(dsf) file.
My measurement was percentage improvement in render times of a 3060 and a 5800X.
With CPU+GPU the time was 223 seconds.
GPU only was slightly slower at 227 seconds.
In this particular scene adding the CPU reduced render times by less than 2%.
I say look for the best deal you can get on a pre-built system and to with it, since the GPU prices and availability are the issue:
example: https://www.ibuypower.com/store/Creator-RDY-LCIIRG208
Maybe the single core speed is also way faster than the old CPU as well as more cores then. I had the same GPU when I replaced the CPU, and the lag is gone now.
I wouldn't use CPU with a 3080.
I have a Threadripper and don't use it for renders, although I have a 3090; doesn't matter if I use Blender or Studio, still don't use the CPU.
I use 3090 with 5900X and to my surprise CPU+GPU rendering is actually marginally slower than just using the GPU. I've heard similar stories of people using 3080. This was not the case when I was using 980+i5. I think RTX GPU are getting more and more tuned for raytracing such that CPU hardly matters anymore in Daz Iray rendering.
The rest of Daz is mostly single threaded so paying for extra CPU cores don't benefit in this use case.