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CPU vs GPU in rendering

Hey guys, got a question.

 

To my knowledge, GPU has always been faster than CPU in video rendering (and may other rendering applications?). If this is the case, why is everyone so excited about multi-core CPUs like Threadripper when it comes to rendering?

 

Please enlighten me, thank you.

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It all depends on the program but by and large many cores and lots gpu power are both used.

 

Also, TR is wonderful for rendering just because of the crazy amount pcie lanes FOR the gpu's. 

Want to custom loop?  Ask me more if you are curious

 

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What GPUs can do they do well, but they can't do everything. Some things can't be done on GPUs or are done better on CPUs due to more flexibility due to the cores being more robust.

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because rendering is moving pixels, and GPUs are made to move pixels.

 

or in a more technical answer..

GPU's are designed to handle very parallelised workloads and move large amounts of data around quickly, in this specialisation however giving up some more "generic" functionality.

CPU's are designed to be a very universal architecture, more focussed on being capable of doing all calculations, than on the efficiency of a single type of computation.

 

that however doesnt mean that the CPU's sitting idle when rendering, it still has to tell the GPU what to render, give it the input data it needs to render, store the output data of the render job, and preferably still have headroom for everything on the system that cant be mindlessly pushed to a GPU.

 

also, not every program/editor uses GPU rendering, for a multitude of reasons, and cpu sided x264 to put an example is amazing when you can just "toss cpu cycles" at it in a brute force sort of way, making it more universally capable than for example nvenc and quicksync which are more "thought trough" ways of achieving the same thing, but unfortunately only shine in the exact case they were designed for.

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Some programs don't have GPU accelerated rendering, and ones that do often have certain limitations of the technology they can use, such as CUDA or others.

Also, GPUs can only do so much, for example sony vegas usually only uses about 25% GPU when rendering. It's not like a game where it will use your GPU at 100% all the time.

Rendering across CPU cores scales up a lot more effectively and is what the majority of people rely on for their rendering.

 

Also, there is a lot of stuff that is not just rendering videos that content creators need to do, and having more CPU cores helps with multitasking, encoding, and other stuff too.

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19 minutes ago, Enderman said:

Also, there is a lot of stuff that is not just rendering videos that content creators need to do, and having more CPU cores helps with multitasking, encoding, and other stuff too.

Oh yeah, totally true.  Multitasking is 100% the reason I went from a 6700k @4.6ghz to a stock (soon to be OC'd) 1700.

Want to custom loop?  Ask me more if you are curious

 

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