Starting at the bottom, in terms of raw power, the RTX 2070 is roughly equivalent to the GTX 1080; the RTX 2080 goes toe to toe with the GTX 1080 Ti; the RTX 2080 Ti is in a league of its own. The 2070 and 2080 have 8GB of GDDR6 RAM; the 2080 Ti has 11GB. All three are based on the company's new Turing architecture, which means they have cores dedicated to AI (Tensor) and ray-tracing (RT).
Expect a fourth card, likely the RTX 2060, to bring the entry price down significantly in the coming months, followed by a slew of cut-down options for budget-minded gamers (the 10 series made its way down to the sub-$100 GTX 1030). There's also room at the top end for expansion: The RTX 2080 Ti Founders Edition can handle 14.2 trillion floating-point operations per second (TFLOPS), while the Turing TU102 chip these new cards are based on pushes that figure up to 16.3 TFLOPS. That's achieved through a mix of higher clock speeds and more CUDA cores (the 2080 Ti has 4,352, the fully configured TU102 has 4,608.)
RTX also arrives with a lot of under-the-hood improvements. There's a faster caching system with a shared memory architecture, a new graphics pipeline and concurrent processing of floating and integer calculations. If that means nothing to you, don't worry too much: The takeaway from that word soup is not only does the RTX range have more raw power, but it uses that power more efficiently.
And that's the key here. Ray-tracing stole the headlines, and I'm intrigued to see how developers use it, but it's efficiency that really excites me about RTX.
The ultimate goal of a game system, be it a $2,000 gaming PC or a $300 Nintendo Switch, is to calculate a color value for each pixel on a screen. Even a simplified guide on how a modern graphics pipeline does this would run the length of a novella, but here's a three-sentence summary: CPUs aren't made to render modern graphics. Instead, a CPU sends a plan for what it wants to draw to a GPU, which has hundreds or thousands of cores that can work independently on small chunks of an image. The GPU executes on the CPU's plan, running shaders -- very small programs -- to define the color of each pixel.
The challenge for both graphics-card manufacturers and game developers, then, is scale. That $300 Switch, in portable mode, typically calculates 27-million pixel values a second, which it can do just fine with a three-year-old mobile NVIDIA chip. If you're targeting 4K at 60FPS (which is what many gamers buying RTX cards want) your system needs to push out close to half-a-billion pixels a second. That puts a huge strain on a system, especially when you consider that your PC isn't just picking these colors out of thin air, and is instead simulating a complex 3D environment in real time as part of the calculations.
There are already plenty of techniques used to reduce that strain. One is rendering all or parts of a scene at a lower resolution and stretching the results out. This is super obvious when you have a game running at 720p on a 1080p screen, but less so when, say, a fog cloud is being drawn at quarter-resolution. And that's what NVIDIA's optimizations are all about: cutting down the quality in places you won't notice.
NVIDIA's new graphics pipeline can employ several new shading techniques to cut corners. In many ways, this builds on less-flexible power-saving measures utilized for VR, like MRS (multi-resolution shading) and LMS (lens-matched shading). In the image above, you're seeing a GPU breaking a scene down into a grid in real time. The uncolored squares are high-detail, and shaded at a 1:1 ratio, just like a regular game scene. The colored ones don't need the same level of attention. The red squares, for example, are only shaded in 4x4 pixel blocks, while more-detailed but non-essential blue squares are shaded in 2x2 blocks. Given the low detail level of those areas of the image, the change is essentially unnoticeable.