DaVinci Resolve Studio – RTX 3080 & 3090 Multi-GPU Performance Scaling

Introduction

DaVinci Resolve is known in the industry as having excellent GPU-acceleration support – greatly benefiting from a powerful (or multiple powerful) video cards. This makes the new RTX 30-series cards from NVIDIA very attractive given the incredible performance we saw in our DaVinci Resolve Studio – NVIDIA GeForce RTX 3080 & 3090 Performance article. If you missed that post, the RTX 3090 is especially impressive as it matches a pair of RTX 2080 Ti 11GB cards while costing $1,000 less and having significantly more VRAM.

But for power users, one GPU is simply not enough. Dual, triple, and even quad GPU configurations are common in high-end Resolve workstations in order to further increase performance. However, the new RTX 30-series cards have a number of issues that, for the moment, prevent these types of configurations.

While Resolve can scale nicely with multiple GPUs, the design of the new RTX 30-series cards presents a significant problem. Not only is the power draw significantly higher (which means more heat is being generated), but the current cooler design on the FE (Founders Edition) cards from NVIDIA and all the 3rd party manufacturers is strictly designed for single-GPU configurations.

On the NVIDIA FE cards, the fan on the front of the card actually blows through the GPU – sucking cool air in from the bottom and exhausting out the top. That means that if you have multiple cards, you will be venting the hot air from one card directly into the intake of the card above it. Multiply this across two, three, or even four GPUs, and you have a recipe for thermal throttling, if not outright system crashes.

The aftermarket cards are not much better. They do not vent through the card, but almost all of them do not vent any of the waste heat outside the system and instead rely on the chassis fans to take care of removing the hot air out of the system. That is feasible for a single GPU, but with multiple cards what ends up happening is that the air simply gets recycled between the cards, getting hotter, and hotter, and hotter.

The good news is that Gigabyte has already announced a blower-style version of the RTX 3090 (the GeForce RTX 3090 TURBO 24G) which should in theory make multi-GPU configurations of the RTX 3090 possible. Oddly, there is no word on an RTX 3080 model as of yet, but we are hopeful that other manufactures will take note and make blower-style models of the RTX 3080 and 3090.

In the meantime, we can do some performance testing with multiple RTX 3080 and 3090 GPUs using the cards that are currently available. However, we need to stress that this is very early testing. The RTX 30-series cards have much higher power requirements compared to the previous generation, and the coolers are not optimal for multi-GPU configurations. We do not know yet what will be stable and reliable long-term, but we will likely need to wait for blower-style cards to be released. So, while we are looking at performance in Resolve with multiple cards in this article, we highly recommend waiting until our qualification team determines what will stable and reliable long term.

Test Setup

Listed below is the specifications of the system we will be using for our testing:

*All the latest drivers, OS updates, BIOS, and firmware applied as of September 15th, 2020

To test multiple GPUs, we will be using the fastest platform currently available for DaVinci Resolve – most notably the AMD Threadripper 3970X. Since Resolve utilizes the CPU so heavily, this should minimize the impact of the processor and allow each configuration to perform to its fullest potential.

For the testing itself, we will be using an upcoming version of our PugetBench for DaVinci Resolve benchmark that is not yet available to the public. This new version is very close to being available for download, but since the tests are much better than the version that you can currently download, we opted to go ahead and use it for this comparison.

One thing you might notice is that we only used three RTX 2080 Ti and 3090 GPUs, and just two RTX 3090 GPUs. The reason for not testing quad GPU configurations is simply because we almost never sell that configuration for Resolve. Almost all professional workflows require a video monitoring card for unbiased video, which has to take the place of a GPU. It also requires either a motherboard that we have not qualified or moving to an Intel Xeon platform which is not as good for Resolve overall.

For the RTX 3090, we maxed out at just two cards because the RTX 3090 FE cards are triple-slot, which means we can only fit two of them into our current Threadripper platforms. With certain motherboards, it may be possible to cram three RTX 3090 cards into a single workstation, but that is going to be extremely difficult to do – not to mention likely impossible to keep cool. So until dual-slot blower cards come out, we have to stick with just a dual RTX 3090 configuration for this testing.

Once again, we want to stress that the GPUs we are using are not designed for being used in this manner. It shouldn't affect our results much, but we would absolutely not recommend using this setup for your own workstation.

Raw Benchmark Results

While we are going to go through our analysis of the testing in the next section, we always like to provide the raw results for those that want to dig into the details. If there is a specific codec or export setting you tend to use in your workflow, examining the raw results for that task is going to be much more applicable than our more general analysis.

Overall DaVinci Resolve Studio GPU Scaling Analysis

While many reviewers like to solely look at things like temporal noise reduction (often to an unrealistic degree) or OpenFX that heavily utilize the GPU, we first want to start off by looking at the overall performance we saw from our DaVinci Resolve benchmark with each configuration in order to show what most users would likely experience in their day-to-day work.

GPU scaling in Resolve is interesting to look at because there are so many facets to the application. Much of Resolve does not actually take advantage of the GPU all that much, with the performance when working with bare media or just a simple grade almost always bottlenecked by your CPU rather than your GPU. Because our benchmark looks at such a wide range of tasks in Resolve, the Overall Score – and even the individual 4K and 8K media scores – is not all that exciting.

In fact, if you look at the last chart for the Fusion tests, you will actually see that the performance actually gets worse with multiple GPUs.

So to get a better idea of the maximum performance benefit from using multiple GPUs, we should focus on the "GPU Effects" portion of our benchmark which looks at tasks like noise reduction and various GPU-accelerated OpenFX.

GPU Score Analysis

The GPU effects portion of our benchmarks looks at the performance of individual GPU-accelerated effects such as temporal noise reduction, film grain, lens blur, optical flow, face refinement, and more. In our testing, these effects easily show the largest benefit of having multiple GPUs.

Starting with the dual RTX 3090 configuration, it does extremely well, easily out-performing the triple RTX 2080 Ti setup. This makes dual RTX 3090 not only more affordable (at $3,000 for two 3090s vs $3,600 for three 2080 Tis) but also gives you 24GB of usable VRAM versus the 11GB on the RTX 2080 Ti cards. The current triple-slot design of the RTX 3090 FE cards does mean that you will have a hard time fitting a video monitoring card which is a requirement for most professional workflows, but since we would never recommend using these exact cards in this configuration in the first place, we will give that a pass until the blower-style cards become available.

The dual and triple RTX 3080 configurations also do well, consistently beating the same number of RTX 2080 Ti cards by a solid 30%.

The main thing to take away is that the scaling with multiple cards is no different than what it is with the RTX 20-series cards. Two cards are roughly 50% faster than a single card, while three cards are about double the performance of one card. If we extrapolate this out for those that want a quad GPU setup, four cards should be roughly 2.5x the performance of a single card.

How well does the NVIDIA GeForce RTX 3080 & 3090 perform in DaVinci Resolve Studio?

Power users of DaVinci Resolve Studio love to load up their workstation with multiple GPUs, and doing so with the new RTX 30-series cards is just as effective as it was with the previous generation. However, while each GPU you add can increase the performance in Resolve by roughly 50% for each card, be aware that we would highly recommend waiting for blower-style cards before pulling the trigger on multiple RTX 3080 or 3090 GPUs.

The issue is that the cooler design on the models currently available is designed strictly for use with a single GPU. Whether you are looking at the Founders Edition cards from NVIDIA or one of the various 3rd party designs, these cards are not going to work long-term in a multi-GPU setup. Once blower-style cards become available, the RTX 30-series cards should be an excellent option for a DaVinci Resolve workstation.

The good news is that some manufacturers like Gigabyte have already announced blower-style cards (the GeForce RTX 3090 TURBO 24G) which should work significantly better for this. Of course, we need to wait and see how well those cards are able to handle the higher power draw of the RTX 3090, but at the very least there is still hope for using multiple GeForce RTX 30-series cards and not having to jump up to the more expensive Quadro models that (we assume) are coming down the pipe.

As always, keep in mind that these results are strictly for DaVinci Resolve Studio. If you have performance concerns for other applications in your workflow, we highly recommend checking out our Hardware Articles (you can filter by "Video Card") for the latest information on how a range of applications perform with the new RTX 3080 and 3090 GPUs (including multi-GPU setups when relevant), as well as with different CPUs and other hardware.