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V-Ray CPU Comparison: Skylake-X vs Threadripper

Written on September 1, 2017 by William George
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Introduction

V-Ray, from Chaos Group, is widely used for creating realistic 3D graphics. When rendering those graphics, both the central processor (CPU) and graphics processors (GPUs) can be utilized to increase performance. On the CPU side, rendering generally scales well with both clock speed and core count - but those specifications cannot be directly compared across different brand or generations of processor. Here at Puget Systems we do real-world testing to ensure we provide our customers with the right computer for their needs.

In this article we are going to look at the latest CPU options from Intel and AMD, both of which have recently released high core count processors that should be great for V-Ray. From Intel we have the Core X series of processors, which were code-named Skylake X. They come in 6- to 12-core models currently, though up to 18-core variants will be coming in the future. Up against these chips are AMD's new Threadripper processors, based on a pair of Zen chips combined into a single package. We'll be looking at the 12- and 16-core models in that family to see how they stack up against Intel's traditional lead in this application.

We are also including several other CPU platforms in this article, as points of comparison. We've got Intel's lower core count Kaby Lake chips, along with AMD's similar Ryzen line. Intel's Xeon versions of the Skylake X are also present, called Skylake W or Xeon W depending on where you look. And to top things off, a dual Xeon configuration is included as well - to show what can happen if you put two powerful processors together.

Test Setup

To see how these different CPUs perform in V-Ray, we ran the free benchmark in CPU mode on the following configurations:

These test configurations include a wide range of Intel and AMD processors. CPU-based rendering in V-Ray is known to scale well across multiple cores, so the lower core count processors are mostly here for reference. Such 4, 6, and even 8 core chips are common on home and gaming computers, as well as office workstations, but they don't really hold up well under heavily threaded applications like rendering. Ideal performance for rendering will be found with 10+ cores, and a while the focus of this particular article is on single-CPU performance we included a dual Xeon processor setup as an example of how well such a system does with heavily threaded workloads.

The results presented below are from V-Ray Benchmark 1.0.6, which is a free benchmark released by Chaos Group. It is designed to test CPU and GPU performance within V-Ray without requiring a full installation of that software. Since the focus of this article is on CPU performance we only ran the CPU portion of the benchmark, which gives a time in seconds for how long it took to render a single scene. The rendering can also be watched in real-time during the benchmark, and the benefit of additional cores can be seen visually that way.

It is also worth noting that there are some differences in the amount and speed of RAM across the various test platforms, as well as the video card utilized. We prefer to use the speed of memory that each CPU is rated for, according to its manufacturer, but in the case of the new Xeon W processors we couldn't get the rated speed running on the motherboard sample we have. Intel processors generally show little impact from small changes in memory speed, though, so that shouldn't impact the results much. Likewise, since this benchmark focuses on the CPU, the difference between the two video cards used will not affect the results.

Benchmark Results

Here are the results for the various CPUs we tested in V-Ray Benchmark 1.0.6:

V-Ray Benchmark 1.0.6 Results

Since rendering in V-Ray is a heavily threaded application, there is a clear spread between the different processors based on core count. The dual Xeon, with a total of 28 cores, definitely wins out - but that is a much more expensive system and is really just included here as a point of reference. Among the single CPU workstations, AMD's 16-core 1950X is the fastest by a healthy margin. Next up is Intel's 12-core i9 7920X, which beats out AMD's 12-core variant in performance... but costs even more than the 16-core model. Intel's 10-core is the same price as the 16-core from AMD but barely beats their 12-core model. The rest of the processors fan out from there in accordance with the number of cores they have.

An interesting thing to note here is that Intel's Core X and Xeon W lines match up very closely on a per-core basis. That makes sense as these are based on the same Skylake technology under the hood, but Intel charges a lot more for the Xeon variants since they support features like ECC memory. If that matters to you then they are a viable option in terms of performance, but be aware that you will pay a premium for them. Many AMD processors also support ECC (though not registered) memory, but not all motherboards do.

It is also worth noting that Intel has 14, 16, and even 18-core models coming soon in the Core X series. When they are released later this year some of them will likely beat out AMD's Threadripper chips for the top performance spot in single CPU rendering, but at a higher price tag. AMD and Intel both have server-class processors with even more cores as well: up to 32 on AMD's EPYC and up to 28 from Intel's Xeon Platinum line. With their focus on the multi-CPU server segment those may not come into play here, but if a manufacturer puts out a single-socket workstation motherboard that is compatible with either of those platforms then they may be worth a look.

Conclusion

Here is a summary of V-Ray multi-core performance between just the top two Skylake X and Threadripper processors:

V-Ray Benchmark 1.0.6 Skylake X vs Threadripper Comparison

Based on these test results, and as of the writing of this article, Threadripper is clearly in the lead for CPU based rendering in V-Ray. The 16-core 1950X not only beats the 12-core i9 7920X, it also costs less. Looking to the near future, Intel's 14-18 core processors are likely to take back the performance lead - but will still cost more than AMD's offerings. We will test those when they become available and publish additional results at that time. We will also use this data to craft our recommended systems for V-Ray going forward.

V-Ray Workstations and Render Nodes

1 CPU, 1-2 GPUs
Compact Workstation

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1 CPU, 1-4 GPUs
Tower Workstation

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2 CPUs, 1-4 GPUs
Tower Workstation

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2 CPUs, 1-4 GPUs
1U Rackmount

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Tags: CPU, Rendering, Chaos, Group, V-Ray, Performance, Processor, Intel, AMD, Core, i7, i9, Ryzen, Threadripper