CPU Tests: Rendering

Rendering tests, compared to others, are often a little more simple to digest and automate. All the tests put out some sort of score or time, usually in an obtainable way that makes it fairly easy to extract. These tests are some of the most strenuous in our list, due to the highly threaded nature of rendering and ray-tracing, and can draw a lot of power. If a system is not properly configured to deal with the thermal requirements of the processor, the rendering benchmarks is where it would show most easily as the frequency drops over a sustained period of time. Most benchmarks in this case are re-run several times, and the key to this is having an appropriate idle/wait time between benchmarks to allow for temperatures to normalize from the last test.

Blender 2.83 LTS: Link

One of the popular tools for rendering is Blender, with it being a public open source project that anyone in the animation industry can get involved in. This extends to conferences, use in films and VR, with a dedicated Blender Institute, and everything you might expect from a professional software package (except perhaps a professional grade support package). With it being open-source, studios can customize it in as many ways as they need to get the results they require. It ends up being a big optimization target for both Intel and AMD in this regard.

For benchmarking purposes, we fell back to one rendering a frame from a detailed project. Most reviews, as we have done in the past, focus on one of the classic Blender renders, known as BMW_27. It can take anywhere from a few minutes to almost an hour on a regular system. However now that Blender has moved onto a Long Term Support model (LTS) with the 2.83 release, we decided to go for something different.

We use this scene, called PartyTug at 6AM by Ian Hubert, which is the official image of Blender 2.83. It is 44.3 MB in size, and uses some of the more modern compute properties of Blender. As it is more complex than the BMW scene, but uses different aspects of the compute model, time to process is roughly similar to before. We loop the scene for at least 10 minutes, taking the average time of the completions taken. Blender offers a command-line tool for batch commands, and we redirect the output into a text file.

(4-1) Blender 2.83 Custom Render Test

For Blender, we're seeing that SMT gives some extra performance in 64C mode, and comparing TR to TR Pro shows a big jump for the 3955WX over the 3960X despite having fewer cores, whereas the 32c TR is slightly faster than the 32c TR Pro. At 64c, there's little difference.

Corona 1.3: Link

Corona is billed as a popular high-performance photorealistic rendering engine for 3ds Max, with development for Cinema 4D support as well. In order to promote the software, the developers produced a downloadable benchmark on the 1.3 version of the software, with a ray-traced scene involving a military vehicle and a lot of foliage. The software does multiple passes, calculating the scene, geometry, preconditioning and rendering, with performance measured in the time to finish the benchmark (the official metric used on their website) or in rays per second (the metric we use to offer a more linear scale).

The standard benchmark provided by Corona is interface driven: the scene is calculated and displayed in front of the user, with the ability to upload the result to their online database. We got in contact with the developers, who provided us with a non-interface version that allowed for command-line entry and retrieval of the results very easily.  We loop around the benchmark five times, waiting 60 seconds between each, and taking an overall average. The time to run this benchmark can be around 10 minutes on a Core i9, up to over an hour on a quad-core 2014 AMD processor or dual-core Pentium.

(4-2) Corona 1.3 Benchmark

Corona is another bencmark where having SMT enabled does push the results higher, and there's no real difference between TR and TR Pro here. 

Crysis CPU-Only Gameplay

One of the most oft used memes in computer gaming is ‘Can It Run Crysis?’. The original 2007 game, built in the Crytek engine by Crytek, was heralded as a computationally complex title for the hardware at the time and several years after, suggesting that a user needed graphics hardware from the future in order to run it. Fast forward over a decade, and the game runs fairly easily on modern GPUs.

But can we also apply the same concept to pure CPU rendering? Can a CPU, on its own, render Crysis? Since 64 core processors entered the market, one can dream. So we built a benchmark to see whether the hardware can.

For this test, we’re running Crysis’ own GPU benchmark, but in CPU render mode. This is a 2000 frame test, with medium and low settings.

(4-3a) Crysis CPU Render at 320x200 Low

Crysis CPU only has two main limitations: either 32 threads, or 23 cores. We typically run across 16 cores with all threads, and this benchmark tends to prefer cores with high IPC. The 3955WX seems to perform best here, although the Intel options come out ahead.

POV-Ray 3.7.1: Link

A long time benchmark staple, POV-Ray is another rendering program that is well known to load up every single thread in a system, regardless of cache and memory levels. After a long period of POV-Ray 3.7 being the latest official release, when AMD launched Ryzen the POV-Ray codebase suddenly saw a range of activity from both AMD and Intel, knowing that the software (with the built-in benchmark) would be an optimization tool for the hardware.

We had to stick a flag in the sand when it came to selecting the version that was fair to both AMD and Intel, and still relevant to end-users. Version 3.7.1 fixes a significant bug in the early 2017 code that was advised against in both Intel and AMD manuals regarding to write-after-read, leading to a nice performance boost.

The benchmark can take over 20 minutes on a slow system with few cores, or around a minute or two on a fast system, or seconds with a dual high-core count EPYC. Because POV-Ray draws a large amount of power and current, it is important to make sure the cooling is sufficient here and the system stays in its high-power state. Using a motherboard with a poor power-delivery and low airflow could create an issue that won’t be obvious in some CPU positioning if the power limit only causes a 100 MHz drop as it changes P-states.

(4-4) POV-Ray 3.7.1

POV-Ray seems to prefer the 64C/64T variants of Threadripper, but the difference between TR and TR Pro is ever so slightly in favor of the higher frequency TR processors.

V-Ray: Link

We have a couple of renderers and ray tracers in our suite already, however V-Ray’s benchmark came through for a requested benchmark enough for us to roll it into our suite. Built by ChaosGroup, V-Ray is a 3D rendering package compatible with a number of popular commercial imaging applications, such as 3ds Max, Maya, Undreal, Cinema 4D, and Blender.

We run the standard standalone benchmark application, but in an automated fashion to pull out the result in the form of kilosamples/second. We run the test six times and take an average of the valid results.

(4-5) V-Ray Renderer

V-Ray shows benefit from having all 128 threads enabled, and it is interesting here that the performance difference between the 32c and 64c/64t options is next to zero. The W-3175X does well here by contrast, beating out the 32c variants.

Cinebench R20: Link

Another common stable of a benchmark suite is Cinebench. Based on Cinema4D, Cinebench is a purpose built benchmark machine that renders a scene with both single and multi-threaded options. The scene is identical in both cases. The R20 version means that it targets Cinema 4D R20, a slightly older version of the software which is currently on version R21. Cinebench R20 was launched given that the R15 version had been out a long time, and despite the difference between the benchmark and the latest version of the software on which it is based, Cinebench results are often quoted a lot in marketing materials.

Results for Cinebench R20 are not comparable to R15 or older, because both the scene being used is different, but also the updates in the code path. The results are output as a score from the software, which is directly proportional to the time taken. Using the benchmark flags for single CPU and multi-CPU workloads, we run the software from the command line which opens the test, runs it, and dumps the result into the console which is redirected to a text file. The test is repeated for a minimum of 10 minutes for both ST and MT, and then the runs averaged.

(4-6a) CineBench R20 Single Thread(4-6b) CineBench R20 Multi-Thread

CBR20 scales up to 128 threads no problem, but we're seeing a preference in TR over TR Pro in this test where memory bandwidth doesn't matter much.

Power Consumption CPU Tests: Encoding


View All Comments

  • Spunjji - Friday, July 16, 2021 - link

    Having seen how modern processors behave with insufficient cooling, Threska's right that it won't get "fried", but you're correct to infer that it would result in unpredictably sub-optimal performance.

    Anecdotally, I had a friend with a Sandy Bridge system with a cooling issue that he only noticed when he bought a new GPU and ran 3DMark and got unexpectedly low results. The "cooling issue" was that the stock heatsink wasn't even making contact with the CPU heat-spreader; he'd been gaming with the system for 3 years by that point. 😬
  • serpretetsky - Friday, July 16, 2021 - link

    I had to do some thermal shutdown testing on some consumer intel cpu. I forgot which one. Maybe i5/i7 8000 series?

    With server CPUs this was usually pretty easy, remove fan, and wait for shutdown. With the consumer CPU it kept running. So i completely removed the heatsink, the thing simply downclocked to 800 MHz, and continued running happily with no heatsink. Booted to linux, ran everything great, and no heatsink (actually once it booted to linux I think it even started clocking back up once in a while). I had get a hot-air soldering gun to heat it up till shutdown.
  • mode_13h - Saturday, July 17, 2021 - link

    5-10 years ago, there was a heatsink gasket where you have to get near 100 degrees C to melt the material so it fuses with the heatsink and CPU. I forget the name, but I'm wondering if it's even possible to do that any more. Reply
  • skaurus - Wednesday, July 14, 2021 - link

    That's great analysis. Reply
  • Threska - Wednesday, July 14, 2021 - link

    It would be nice to see how these MBs do with VFIO since that has considerations most users don't. Reply
  • mode_13h - Wednesday, July 14, 2021 - link

    Ian, is the source code for your 3DPM benchmark published anywhere? If not, it would be nice if we could see it and compare the AVX2 path with the AVX-512 one. Also, maybe someone could add support for ARM NEON or SVE. Reply
  • techguymaxc - Wednesday, July 14, 2021 - link

    I'm slightly confused by the concluding remarks.

    "Performance between Threadripper Pro and Threadripper came in three stages. Either (a) the results between similar processors was practically identical, (b) Threadripper beat TR Pro by a small margin due to slightly higher frequencies, or (c) TR Pro thrashed Threadripper due to memory bandwidth availability. That last point, (c), only really kicks in for the 32c and 64c processors it should be noted. Our 16c TR Pro had the same memory bandwidth results as TR, most likely due to only having two chiplets in its design."

    A and B are observable, but C only proves true in synthetic benchmarks (and Pi calculation). Is there a real-world use-case for the additional memory bandwidth, outside of calculating Pi?
  • Blastdoor - Wednesday, July 14, 2021 - link

    The advantage shows up with multi-threaded SPEC. SPEC is essentially a composite of a suite of real-world tasks. I guess you could call it 'synthetic' due to it being a composite, but the individual tasks don't strike me as 'synthetic.' For example, here's a description of namd: https://www.spec.org/cpu2017/Docs/benchmarks/508.n... Reply
  • techguymaxc - Wednesday, July 14, 2021 - link

    Thanks for that info. It would be nice to see the breakdown of individual test results from the SPEC suite. Reply
  • arashi - Saturday, July 17, 2021 - link

    Bench Reply

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