Minimum Spec CPU for Iray Rendering?

zombiewhacker

Presumably there will be times when a scene is too large for your nVidia card and Studio will drop to CPU.

When that happens, what are the minimum specs you'd need in a good CPU (Intel or Ryzen) to make sure your CPU-only render goes as smoothly and quickly (relatively speaking) as possible?

rokkybum

AMD Threadripper (expensive) or AMD Ryzen 9 3900x will good work. Think about Mainboard for Threadreaper is expensive too. 

And add a lot of RAM, lol.

onix

CPU rendering is super slow and useless, especially if the scene is so complex that it doe not fit in the GPU memory, and I think if you are willing to invest in up that much you probably better just buy GPU with more memory.

Considering CPU  rendering performance It may happen that an expensive CPU will not give that much benefit because memory bandwidth is the real bottleneck for rendering performance.  Most mainstream CPUs already contain GPU unit which can be used for rendering acceleration but memory bandwidth does not allow you to reach any reasonable performance levels
dedicated video cards have very high memory bandwidth and extremely wide data bus where no CPU can even come remotely close

But anyway we have some real tests

https://www.daz3d.com/forums/discussion/341041/daz-studio-iray-rendering-hardware-benchmarking/p1#Section 3.3

Not sure how even to interpret that

kenshaw011267

I never let renders drop to CPU. 

zombiewhacker

@Onix - Thanks for the link, that helps a lot.

@kenshaw011267 - What's your workflow for large scenes, then? Do you use a utility like Scene Optimizer, or does your GPU simply have, like, 80 kazillion GB of RAM?

kenshaw011267

zombiewhacker said:

@Onix - Thanks for the link, that helps a lot.

@kenshaw011267 - What's your workflow for large scenes, then? Do you use a utility like Scene Optimizer, or does your GPU simply have, like, 80 kazillion GB of RAM?

I own scene optimizer and use it if a scene would drop but scenes rarely do. I have a lot of experience with my cards, a 1080ti and a 2070, so I rarely go over 8Gb and usually have a pretty good idea for what will and run scene optimizer before even trying to render if I think the scene is pushing the 2070's limit.

Every couple of months I'll get up in the morning, I do most of my rendering overnight with renderqueue, and a render will have dropped and still be running. I shut it down and the next chance I get I'll look it over and optimize it and get it to run on the GPU(s). The usual issue is a newer environment or character with loads of high resolution maps (I've been seeing more and more 8k maps on stuff). But I never just let a render run to completion on CPU.

Most of my renders are for my VN's and I need to get a reasonable number of scenes rendered a week and I cannot have a single render run overnight that would completely upend my schedule.