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GPU Rendering - NVIDIA RTX A6000 Multi-GPU Scaling

Written on March 26, 2021 by Kelly Shipman
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TL;DR: NVIDIA RTX A6000 Multi-GPU Rendering Performance

Running multiple of NVIDIA's RTX A6000 video cards provides excellent scaling in GPU-based rendering engines!

This is no surprise, as it was true with the RTX 30 Series and other GeForce and Quadro video cards as well, but it is still impressive to see what these cards are capable of when used in sets of two, three, or four. However, it is important to keep cooling and power consumption in mind when putting together a multi-GPU workstation. The professional grade RTX A6000 has a cooler designed to work in tandem with multiple cards. Their power draw is high enough that special attention needs to be payed when using four at the same time.

Introduction

Now that NVIDIA’s professional line of Ampere cards, specifically the RTX A6000, have become available, it’s time we look at how multiple cards scale in a single system. Previously we looked into the scaling performance of the GeForce 30 series cards, however, since then blower-style cards have been removed from the market. This means that to get more than two video cards into a system, and cool them effectively, the RTX A6000 is the only option. We are still waiting on official word regarding any lower-tiered cards such as an A5000 or A4000, and will have articles coving those should they appear.

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Test Setup

Listed below are the specifications of the system we used for our GPU scaling tests:

Test Platform
CPU Intel Xeon W-2235 3.8GHz 6 Core
CPU Cooler Noctua NH-U12DX i4
Motherboard Asus WS C422 SAGE/10G
RAM 8x DDR4-2933 16GB (128GB total)
Video Card 1-4x NVIDIA RTX A6000 48GB PCI-E
Hard Drive Samsung 970 Pro 1TB M.2
Power Supply

Super Flower LEADEX Platinum 1600W

Software Windows 10 Pro 64-bit (Ver. 2009)
Redshift 3.0.33
OctaneBench 2020.1.5
V-Ray Benchmark 5.00.01

One thing to note here is that all testing was done on an Intel Xeon platform. The reason for this is power. NVIDIA’s Ampere line of video cards are power hungry. Each A6000 is rated at 300 watts. That is lower than the 350 watts of the RTX 3090, which in our previous testing was too much to comfortably put into one system.

The largest power supplies commonly available in the US are rated for 1600W of internal component power draw, in large part because of the limits of standard 15 amp electrical circuits. At 300 watts each, that is 1200 watts for quad GPUs, leaving only 400 watts for the CPU, RAM, drives, etc. That seems like a decent amount, but some CPUs like AMD’s Threadripper are rated at 280 watts and can take up more than that under a full load. The Xeon on the other hand is rated at 130 watts, leaving us with much more comfortable headroom for the rest of the components in the system as well as any power spikes the system may experience. For the sake of keeping this focused on the GPU performance, all tests were done on the same platform. We do offer a Threadripper option for those looking for more CPU power but who only want 2-3 video cards.

OctaneBench Results

V-Ray Benchmark Results

Redshift Demo Results

Scaling Analysis

As we have seen in the past, GPU rendering scales extremely well across multiple video cards. Octane and V-Ray both scale nearly perfectly from one to four cards. There are minor differences of a percent or two in either direction, but that is not surprising from test to test anyway.

Redshift doesn’t scale quite as well, but still sees good improvements with each additional card. One thing to note on the Redshift test is that it is rendering a single 1920x1080 frame, and reporting back the time in seconds for that render. With four cards, the image was rendered in 50 seconds, while with a single card it was just shy of three minutes. What these scores likely show us is a limitation of the benchmark more than Redshift’s ability to scale with more GPUs. I suspect that with a more intense render, higher resolution, or over multiple frames, we’d see better scaling. Even still, taking the results at face value and going from three to four video cards, we would save 15 seconds per frame. On a 10 minute, 30 fps animation, that would save 70 minutes per render. That really adds up.

Conclusion

Running multiple of NVIDIA's RTX A6000 video cards provides excellent scaling in GPU-based rendering engines!

This is no surprise, as it was true with the RTX 30 Series and other GeForce and Quadro video cards as well, but it is still impressive to see what these cards are capable of when used in sets of two, three, or four. However, it is important to keep cooling and power consumption in mind when putting together a multi-GPU workstation. The professional grade RTX A6000 has a cooler designed to work in tandem with multiple cards, but their power draw is high enough that special attention needs to be payed when using four at the same time.

Rendering Workstations

Puget Systems offers a range of poweful and reliable systems that are tailor-made for your unique workflow.

Configure a System!

Labs Consultation Service

Our Labs team is available to provide in-depth hardware recommendations based on your workflow.

Find Out More!
Tags: GPU, GPU Scaling, Quad GPU, Hardware Acceleration, NVIDIA GRID, RTX A6000, Render, Rendering, Video Card, Chaos, OTOY, Maxon, Octane, OctaneBench, Redshift
Ampere

https://nvidianews.nvidia.c...
https://www.nvidia.com/en-u...
https://www.nvidia.com/en-u...

Puget, can you please test the new graphics cards?

Posted on 2021-04-13 06:23:21
Kelly Shipman

We plan on it. There is often a delay from when Nvidia announces a product and when we can get one. As soon as we have some in hand, we'll get some articles out.

Posted on 2021-04-13 15:25:51
MarketAndChurch

I'm very excited to see the A4000 reviewed. Maybe the Macpro 6800x Pro Duo too? Just for a baseline performance metrics to measure your PC's against. Would be really cool.

Posted on 2021-09-14 15:33:12
Kelly Shipman

We've been discussing getting some results with the A4000 and A5000. They perform roughly the same as the RTX 3070 and 3080 respectively, so you can get a little bit of an idea from here: https://www.pugetsystems.co...

As far as a Mac Pro with the 6800X, both Octane and V-Ray require CUDA, so no way to run those on that system. Redshift's OSX version is pretty new, and testing that I've seen so far shows it has a way to go: https://www.cgdirector.com/...

Posted on 2021-09-14 16:13:43
MarketAndChurch

Thank you for this. I've got my order in. I know they were based on GA104 so I was expecting 3070 level performance. What I didn't know was how the pricing reflected in terms of performance leap between the A4000 and A5000/A6000. Or how it scaled when you added more of the same card into the system, but having seen your A6000 reviews, I hope the A4000 scales the same in terms of performance as I might get a second card. Thanks on the Mac update, it's great to know its still useless for my work case until Apple Silicon reaches the Mac Pro. Thanks Kelly, keep up the great work, I'm loving these articles.

Posted on 2021-09-14 17:41:48
George Derbyshire

4x A6000 calls for external temperature control. You can get the heat out of the chassis, but then you need to get the hot air away from the PC before it pulls out back in. I recommend an exhaust fan with ducts that vent the heat outside your home or office.

Posted on 2021-04-25 13:59:01