Nvidia has just released the driver to enable Microsoft DirectX Raytracing (DXR) on Pascal GTX 1060 GPUs 6 GB and more. Nvidia has publicly announced its decision to activate DXR in March – a surprise for many since it is the signature of the RTX 20 series. But the move also raised many questions regarding performance, or their absence. Can a GTX 1060 6 GB really draw rays?
The ray tracing has been referred to by many as "grail" graphic rendering. The technology has been around for decades, looking for high-performance silicon, and is finally finding its first breakthrough in the professional rendering scene. Only when Nvidia's RTX 20 generation, announced in the third quarter of 2018, was implemented in real-time within games – enhanced by dedicated silicon in the form of RT cores.
These RT cores are why Nvidia's RTX 20 Series GPUs are able to direct such huge amounts of compute rays onto a stage. Nvidia's RTX 2080 Ti is capable of processing 10 gigabits a second, while the GTX 1080 Ti can barely equal a fraction of that at just 1.1 gigabits per second. This is a huge deficit, which has all but excluded the best Nvidia Turing GPUs from the game "Holy Grail".
However, just a month ago, Nvidia decided to open support for DXR drivers for most of its 10 series, as well as for the GTX 1660 Ti and GTX 1660: two maps built on the foundations of the Turing architecture without RT Cores. This support extends to the desktop and mobile variants of these GPUs and can be downloaded in the latest driver package.
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This also opens DXR support for the most popular graphics card, the GTX 1060 6GB. According to Nvidia, entry-level cards will not be supported due to the limitations of CUDA and VRAM.
Nvidia feels justified in its decision to launch DXR on Pascal, with the intention of launching a wider network among players and attracting more wild developers into the process. But the overall performance of DXR depends on the implementation of ray tracing in the game, hastens to add Nvidia.
"Raytracing is a hybrid graphic technique," says Justin Walker, director of the GeForce office, "which means we're doing traditional rendering and then, depending on the game, we're using ray tracing to get different types of And depending on what effect they are trying to use, there is actually a very different ray tracing workload that will be presented to the GPU. "
Walker divides ray tracing in today's games into four implementations:
- Ambient occlusion
- Global illumination
Each of these workloads requires different processes and techniques. Some may require a graphics processor to calculate a large number of rays and complex bounce paths, while others have much more localized and low impact effects. This is essential to the disparity of performance in the game between graphics cards capable of unloading these very demanding workloads (RTX 20 series) on cards that can not (GTX Series 10).
The amount of ray tracing work presented at the GPU is very different
In the lowest order of impact on the performance level (although this depends on the implementation of each set), the following should be done: ambient occlusion <shadows <reflections <in overall light.
I put the GTX 1060, GTX 1660 and RTX 2060 – three 'generations' of Nvidia's 'classic' graphics cards at the disposal of a suite of reference games perfectly tuned to see how cards devoid of RT Hearts are drawn in the face of reality And to see the impact of each implementation of ray tracing on performance.
Ambient occlusion is an effect often used in games to realistically darken areas that light is unable to reach due to the presence of nearby objects. The localized nature of this effect, explains Walker, allows him to be relatively little solicited. Although it requires many rays, it does so in a very small area. These short spokes require less computation and should therefore have the least impact on Pascal graphics cards.
"Ambient occlusion is only affected by near geometry, right?" Says Walker. "If the geometry is farther away, it will not affect the shading in this area. So we do not need to draw all the way until it reaches another geometry: we can have very short rays. "
Reflections' demonstration, which uses ambient occlusion by ray tracing, is an applicable benchmark. However, if the ambient occlusion in the scene has little impact, it is complemented by complex reflections, which bounce between many surfaces. As a result, Pascal struggles fiercely, averaging only one-digit fips.
PCGamesN test bench: Intel i7 8700K, MSI MPG Z390 Game Edge AC, 16 GB of Corsair Dominator DDR4, Corsair HX1200i, Philips BDM3275
It should also be noted that the Reflections demo uses DLSS, which, due to the lack of Tensor cores, can not work on the GTX 10 and 16 graphics cards. Nvidia even stated that this could be detrimental to performance.
However, ambient occlusion may be a use of ray tracing that Pascal can almost handle. Although this is not the most visually exciting use of DXR, either.
This ray tracing effect can produce realistic and dynamic shading, regardless of the amount or type of lighting. By tracing the path of light in a scene and its interaction with objects, you can achieve realistic shading in a way previously impossible with pre-lit lighting scenes.
And although it can be very expensive for a GPU, there may be a good side for Pascal. It all boils down to game developers, because the impact of ray lighting on performance depends on the amount and shape of lighting used in the game world.
If you reduce the number of lights or objects in a scene, or if you assign a shadow, you can dramatically reduce the number of beams needed to render that scene in real time.
"If there's only one object in the scene, it's not necessary to do a lot of ray tracing to determine how shaded it is," Walker says. "But if you have multiple objects and you have a very complex geometry, you will of course need a lot more rays to determine where all the shadows will be in the scene."
Shadow of the Tomb Raider is your best bet for acceptable performance within the current DXR-compatible limited library. It only uses shadow tracing and granularity in the settings menu means that even a GTX 1060 can handle heat. But these shadows compatible with Pascal are also quite difficult to detect. You may end up deactivating DXR to save time.
Ray-shaped reflections can be extremely detrimental to the frame rates involved, as evidenced by the performance of Battlefield V at launch. At first, DICE was trying to use ray tracing on all surfaces, which is a very difficult task in computation. However, working with Nvidia, DICE has found a solution. Rather than dissipating the rays of each surface of the game, he would only try to do it with those who were particularly bright or reflective – like puddles, windows and metal.
The result is much less demanding. A Battlefield V scene is evaluated on areas that require ray tracing and those that do not. This approach could be implemented further in games to reduce the load on traditional GPU silicon in the absence of RT cores.
The science fiction FPS Atomic Heart is a perfect counterpoint to the low-impact reflections of Battlefield V, however. It uses much more complex reflections, reflections on each other to add more realism and depth to a scene. However, this kills the Pascal GPU.
"So, in Atomic Heart, it's interesting," says Walker, "because there is a much more advanced thinking effect, and on top of that, there is also a shadow effect. ray tracing and ray tracing demand on the GPU. "
Still, there is something to say about the performance of the GTX 1660 in Atomic Heart. Of course, it's still a complete mess for the games, but optimizations within the Turing architecture, such as simultaneous execution, allow the GTX 1660 to almost double the GTX 1060 score.
The new technology demo Justice RTX and 3DMark Port Royal both use advanced thinking. As such, it is not expected that neither one nor the other will benefit from the graphics cards of the 10 series.
The most demanding of all is global enlightenment. It's a bit in the name, is not it? While most techniques can be located in one way or another, overall illumination is widespread everywhere and at any time, and makes it very expensive.
Each ray is responsible for shading a pixel based on the geometry and lighting that surrounds it, creating a scene with variable brightness. However, the amount of rays needed for operation is enormous, with each pixel requiring at least a single ray that bounces off the stage.
Global lighting is often predefined in a title, which avoids making a scene remote from the client PC. However, the resulting scene is static, unable to react to the environment that surrounds it. To achieve this, you must be prepared to spend valuable GPU resources, ideally at the same time as dedicated silicon.
As you can see in Metro Exodus, all these shelves are too difficult to manage for Pascal. Even Turing's optimizations offer no tangible benefit to the performance of the GTX 1660, as both maps struggle to reach 20 fps.
Pascal can only manage a few of the four implementations. And they are considerably mitigated at that. There is at least a minimum of performance in Shadow of the Tomb Raider and Battlefield V with minimal activated ray tracing.
And while there may be a glimmer of hope for a low-impact, future-oriented granular DXR, you also do not want to over-mitigate your graphics settings to achieve readable frame rates with activated ray tracing. Without dedicated silicon, rendering is high and most effects are expensive. It's also a sufficiently realistic graphical improvement for your brain to completely ignore once you're immersed in the game. But what's remarkable is that your graphical settings have gone from ultra to medium / down. And ray tracing is not worth the loss of fidelity and quality at the expense of conventional performance.
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Without the tensor nuclei on the matrix, Nvidia's neural network loses all its intelligence. Thus, even the DLSS can not come to the rescue of pascal GTX cards as the RTX 20 series does.
Perhaps better to use the simultaneous floating-point and integer optimizations of the Turing series 20 and The cards of the 16 series will be the most interesting in the coming years. But this point of inflection could be very far away. There is still only a handful of games on the market that can use DXR, RT Cores or not.
So can you use ray tracing on a GTX 1060? No. At least, you should not. The cost of ray tracing is too high, and you'd better use your limited treatment elsewhere in the process.