The NVIDIA Turing GPU Architecture Deep Dive: Prelude to GeForce RTX
by Nate Oh on September 14, 2018 12:30 PM EST
It’s been roughly a month since NVIDIA's Turing architecture was revealed, and if the GeForce RTX 20-series announcement a few weeks ago has clued us in on anything, is that real time raytracing was important enough for NVIDIA to drop “GeForce GTX” for “GeForce RTX” and completely change the tenor of how they talk about gaming video cards. Since then, it’s become clear that Turing and the GeForce RTX 20-series have a lot of moving parts: RT Cores, real time raytracing, Tensor Cores, AI features (i.e. DLSS), raytracing APIs. All of it coming together for a future direction of both game development and GeForce cards.
In a significant departure from past launches, NVIDIA has broken up the embargos around the unveiling of their latest cards into two parts: architecture and performance. For the first part, today NVIDIA has finally lifted the veil on much of the Turing architecture details, and there are many. So many that there are some interesting aspects that have yet to be explained, and some that we’ll need to dig into alongside objective data. But it also gives us an opportunity to pick apart the namesake of GeForce RTX: raytracing.
While we can't discuss real-world performance until next week, for real time ray tracing it is almost a moot point. In short, there's no software to use with it right now. Accessing Turing's ray tracing features requires using the DirectX Raytracing (DXR) API, NVIDIA's OptiX engine, or the unreleased Vulkan ray tracing extensions. For use in video games, it essentially narrows down to just DXR, which has yet to be released to end-users.
The timing, however, is better than it seems. A year or so later could mean facing products that are competitive in traditional rasterization. And given NVIDIA's traditionally strong ecosystem with developers and middleware (e.g. GameWorks), they would want to leverage high-profile games for ringing up consumer support for hybrid rendering, which is where both ray tracing and rasterization is used.
So as we've said before, with hybrid rendering, NVIDIA is gunning for nothing less than a complete paradigm shift in consumer graphics and gaming GPUs. And insofar as real time ray tracing is the 'holy grail' of computer graphics, NVIDIA has plenty of other potential motivations beyond graphical purism. Like all high-performance silicon design firms, NVIDIA is feeling the pressure of the slow death of Moore's Law, of which fixed function but versatile hardware provides a solution. And where NVIDIA compares the Turing 20-series to the Pascal 10-series, Turing has much more in common with Volta, being in the same generational compute family (sm_75 and sm_70), an interesting development as both NVIDIA and AMD have stated that GPU architecture will soon diverge into separate designs for gaming and compute. Not to mention that making a new standard out of hybrid rendering would hamper competitors from either catching up or joining the market.
But real time ray tracing being what it is, it was always a matter of time before it became feasible, either through NVIDIA or another company. DXR, for its part, doesn't specify the implementations for running its hardware accelerated layer. What adds to the complexity is the branding and marketing of the Turing-related GeForce RTX ecosystem, as well as the inclusion of Tensor Core accelerated features that are not inherently part of hybrid rendering, but is part of a GPU architecture that has now made its way to consumer GeForce.
For the time being though, the GeForce RTX cards are not released yet, and we can’t talk about any real-world data. Nevertheless, the context of hybrid rendering and real time ray tracing is central to Turing and to GeForce RTX, and it will remain so as DXR is eventually released and consumer-relevant testing methodology is established for it. In light of these factors, as well as Turing information we’ve yet to fully analyze, today we’ll focus on the Turing architecture and how it relates to real-time raytracing. And be sure to stay tuned for the performance review next week!
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bernstein - Friday, September 14, 2018 - link
a lot of this will also depend on what kind of silicon ends up in the next playstation & xbox generation...Spunjji - Monday, September 17, 2018 - link
Isn't that already pretty much pinned to AMD? AFAIK Navi is pretty much the consumer interpretation of AMD's PS5 design. Microsoft really aren't likely to jump ship because of their history with Nvidia.Yojimbo - Saturday, September 15, 2018 - link
I think Turing's price/perf ratio will be better than Pascal's. It's the increase in price/performance that is not spectacular. But since AMD isn't releasing anything at all, that doesn't reflect negatively on Turing in any way.I don't know why people are throwing around this "50% of transistors" idea. Where is this information coming from?
Of course Turing will be crushed by a next generation of 7 nm GPUs that is architected equally as well, as such GPUs will have both additional time for architectural improvements and the advantage of a full node shrink. That will be true for both hybrid and raster-only rendering. And it would have been true for raster rendering no matter if RT cores were included or not.
It sounds like NVIDIA is providing the DLSS service to developers for free. I'd expect DLSS usage to be widespread for any developers interested in making games geared towards the 4K market.
I am guessing that Microsoft, at least, will want a raytracing-capable GPU in its next console. I doubt they would spend the effort to make the DXR API extension and then leave the technology out of their console, especially considering the convergence of console and PC gaming they seem to be pushing for.
jwcalla - Friday, September 14, 2018 - link
This is probably my first disinterested nvidia launch. Tensor cores and ray tracing don't really get me excited. I can't imagine half a die used for that stuff. Do the graphics really look that much better? Does hyper-realism even matter?Dizoja86 - Friday, September 14, 2018 - link
It doesn't even have to be hyper-realism. Just the basic limitations you can see with rasterized reflections in the Battlefield V tech demo paints a strong case for the use of ray-tracing. Being able to see reflections of objects that aren't directly on the screen in front of you seems like an important thing to move towards.HollyDOL - Saturday, September 15, 2018 - link
classic rasterized shading and reflection is basically one big cheat on human eye. Imagine something along mp3 128kbit being 'cd quality'. Trying to get that cheat closer and closer to 'reality' is more and more a challenge and resource eater. Ray-Tracing _should_ be able to quite simplify the issue on development front in future. And that's not considering possible visuals quality raise.Tamz_msc - Saturday, September 15, 2018 - link
Lol, players are complaining that in BF V it is hard to distinguish between friendlies and enemies. Adding RTX reflections to the mix would just make it worse.jwcalla - Saturday, September 15, 2018 - link
Watching the Battlefield tech demo (and the others), I didn't think it added a lot of value. When you analyze it side-by-side with a magnifying glass, yes, you can see some differences. I just don't think they're that dramatic and in the heat of game play you're not even going to recognize it. The improvements to global illumination look good though.I just feel like the industry has lost a lot of focus.
RSAUser - Saturday, September 15, 2018 - link
In a game like BF V, you're not just going to stand there looking at reflections, and it's going to hammer your frame rate/force you to go to 1080p or lower.I'd rather turn it off and have a high fps on 4k, tyvm, same as near everyone turned off hairworks for witcher 3, though with that it was at least single player so you'd sacrifice performance for visuals.
Dizoja86 - Friday, September 14, 2018 - link
Sometimes I get frustrated with Anandtech, but being able to have these fantastic articles when new technology is released is why I keep coming back.