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Comment by thdrdt | Hacker News Reader

I'm not sure your CPU will be faster. I'm using Blender on a Ryzen 9 3900x with a RTX 2070S.

The CPU is never faster than the GPU. CPU + CUDA is way faster, but when I use OptiX (RTX) it is unbelievable how fast it is.

The GPU Raytracer just shines here.

The Blender benchmarks: https://opendata.blender.org/

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I don't know, the 3970X has nearly 3 times as many cores as your 3900X. You may be right if pitted against an OptiX GPU, but that's a bit unfair since that entire generation's raison d'etre is raytracing-specific hardware - my point concerned GPGPU, with raytracing as an incidental example. nVidia can't redesign their GPUs for every workload that GPUs struggle with.

If you look at the Blender benchmarks you see that the 64 core Threadripper is faster than any GPU. But the price is steep for that CPU (almost $4000). So while CPU's can be faster the question is if it is relevant. Because you still need a GPU next to that Threadripper for some graphics (if you need graphics).

That's an interesting benchmark.

There's quite considerable variation in the device ranking if you look at each scene render time - the GPU is faster on the quicker-to-render (sub 1 min) scenes, but slower on the slower-to-render scenes (1+ min).

I wonder why that is? I see the 3990X is hugely faster than anything at these slow scenes, which is pretty interesting.

I'm not familiar with rendering, but in the deep learning world it is moderately easy to get considerable speed-ups by using multiple GPUs. Is the same possible here?

I am not sure if this is true for the benchmarks but last week they fixed a bug in (I believe) hair rendering. Render times went from 45 to 5 minutes.

So it all depends in what is being rendered and how a render core is optimized for it.

Also things like b-tree calculations and other algorithms might influence this.

The Nvidia 2xxx series are optimized for ray tracing though, so not sure if comparing with their 1xxx cards make sense.

Well the comparison is between CPU and GPU. Will there come a point that an affordable CPU is faster than a GPU?

Maybe that time will come but I am not sure if that will happen soon.

They are not "optimized" strictly speaking. Thousands of CUDA cores on them don't do ray tracing, it is done on a separate hardware which just happens to sit on the same chip. Add RTX cores to Threadripper crystal and you will get the same result.

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