V-Ray Next CPU Roundup: AMD Ryzen 3, AMD Threadripper 2, Intel 9th Gen, Intel X-series

Introduction

AMD's new Ryzen 3rd generation processors feature both an increase in core count and per-core performance, both of which directly improve rendering speeds in V-Ray Next. In this article we will take a look at how they stack up to other AMD and Intel processors in this application, both in the pure CPU and GPU+CPU render pipelines. We also took a look at rendering in Cinema 4D in another article.

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Test Hardware

For this roundup we have several models in the new Ryzen 3rd Gen family – along with a couple of older 2nd Gen models, AMD's Threadripper 2nd Gen lineup, and Intel's mainstream 9th Gen Core and high performance Core X processors. The main results are all using the same memory: 16GB DDR4 modules running at 2666MHz (4 of them on the Ryzen and Core, 8 on Threadripper and Core X). This was selected to ensure a fair comparison, but because Ryzen also officially supports higher speed memory in certain configurations we tested the new 3rd Gen chips at 3200MHz as well. Those results are included here too, but in a separate set of charts near the end.

Benchmark Details

We used the latest version of Chaos Group's V-Ray Next Benchmark for this comparison, and it includes tests for both CPU-only and GPU+CPU rendering. This is somewhat novel as most GPU rendering engines do not use the CPU at all – but in V-Ray Next, they have implemented CUDA emulation on the CPU to improve performance a bit. Even the fastest CPU doesn't add as much performance in this mode as a single high-end video card, but who would turn down additional performance during renders for no added cost?

With the information we have gathered, then, we put together three charts. The first is the CPU-only performance, the second is GPU+CPU, and the third is the CPU by itself but in GPU mode. The first and third charts, then, are really the most important when considering which CPU to pick for this application – depending on which rendering pipeline you plan to use. Please also note that the selection of CPU (and motherboard) will impact how many video cards you can use, so if you are going the GPU route you can fit more cards in systems which use higher-end processors.

Results

A note about the color coding used here: AMD Threadripper chips are shown in orange, Ryzen is red, and all Intel processors are blue.

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Analysis

In CPU mode, shown on the first chart, Intel's Core X and AMD's Threadripper processors lead the results – which makes perfect sense, given their high core count. However, the new 12-core Ryzen 9 3900X does remarkably well too: it matched the performance of the 16-core Threadripper 2950X for a couple hundred dollars less! The 8-core Ryzen 3rd Gen chips didn't quite match Intel's processors with the same core count, but they are very close – far closer than the 2nd Gen 2700X, which is about 15% further behind.

GPU mode, best shown in the third chart, seems to be even better threaded… and it looks like AMD's architecture is also more favorable. Here, the biggest Threadripper CPUs take the top spots by a wide margin – and the Ryzen 9 3900X beats Intel's Core i9 9920X as well.

Ryzen 3rd Gen Memory Comparison

Most CPUs are rated by manufacturers to support specific speeds of memory, and AMD's new Ryzen 3rd Gen chips are no exception. In this case, the official memory support varies depending on how many modules you have installed and whether they are single- or dual-rank. Tom's Hardware conveniently published these details, which likely came from AMD's reviewer guide (which we do not have):

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The normal memory we used in this test fits the bottom category on that chart: four sticks of dual-rank memory. As such, testing at 2666MHz was the correct speed according to AMD's official support documents. To get the other end of the spectrum, we tested with 3200MHz memory modules as well – which is at the top of the chart, though we still used four 16GB modules in order to keep the total amount of RAM the same. That means this configuration is actually outside of their official support specs, but should still show whether there is anything to gain by going with faster memory on this platform (and in this specific application). Red is 3200MHz, orange is 2666.

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In CPU mode, there is about a 2% performance increase going from 2666MHz to 3200MHz – which is close to the margin of error, but since it was steady across all four processors we tested I think it is safe to say that there is a *very small* benefit to faster memory in this situation. However, to officially stay within AMD's support specs and still use 3200MHz memory would mean only having two sticks of memory… which would mean a limit of 32GB at this time (2 x 16GB), and if you are rendering large or complex scenes that might not be enough. Having renders take 2% longer seems a small price to pay for being able to fit a lot more RAM into the system.

Over on the GPU tests, the two higher-end chips seem to have a similar performance gain – but the others didn't see any benefit. The resolution on results is a lot smaller here, though, with only 2-3 significant digits… or it may just be within margin of error.

Conclusion

It is no surprise that rendering benefits from high core count – as well as clock speed / per-core performance – and AMD has excelled here. The Ryzen 9 3900X is clearly the fastest CPU for rendering in its price range, and with such a small difference between it and the lower core count 3800X and 3700X I don't see any reason to consider those. A $100-200 difference, in the context of a full system build that is probably $2000-5000, is nothing compared to the 40-50% increase in performance gain compared to those models.

With that said, though, there are even faster CPUs available for this sort of workload… so if you have the money to spend, a top-end Intel Core X or AMD Threadripper will render frames more quickly. Those CPUs also support more PCI-Express lanes, so if you plan to use V-Ray Next GPU they will enable more video cards as well as providing more processing power on their own.

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