AMD Radeon RX 6800 XT & Radeon RX 6800 16 GB Graphics Cards Review – Here’s Big Navi!


AMD RDNA 2 'Big Navi' GPU - 1st Gen Ray Accelerator Cores, Mesh Shading, VRSS, Sampler Feedback

Hardware-accelerated ray-tracing is going to be one of the key talking points about RDNA 2 GPUs and not just the desktop parts but all RDNA 2 based products in general. Consoles are going to be relying on ray-tracing as a major selling point and there's a lot of anticipation surrounding AMD's first attempt at ray-tracing.

As we had mentioned in the GPU deep-dive, the main block responsible for handling ray-tracing is known as RA or Ray Accelerator. There's one RA per CU and the flagship parts have up to 80 RAs in total. Each CU can process 4 Ray/Box intersection & a single Ray/Tringle intersection per clock cycle.

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With Ray Accelerator cores, AMD's RDNA 2 can deliver a 10x speedup over a software ray-tracing implementation. Furthermore, the Infinity Cache which we just explained above can also hold very high percentages of BVH working set, thus reducing intersection latency. AMD's RDNA 2 raytracing capabilities would be leveraged for:

  • Dynamic Global Illumination
  • Ray-traced soft shadows from area lights
  • Hybrid reflections mixing compute and screen-space effects with full raytracing

According to AMD, they will allow full raytracing support in games that are based on Microsoft's DXR and Vulkan Raytracing APIs and there are a lot of titles that already do that.

For starters, there are only a handful of titles that are locked behind NVIDIA's RTX implementation and therefore, regarded as a proprietary standard. Major game engines such as Frostbite, Unreal, Seed & Unity are based on Microsoft's DXR APIs. Vulkan Raytracing is also implemented in Id tech's new engines for its next-generation title however, currently, they are only supported for RTX GPUs.

There is a big possibility that developers who have their games based on industry-standard APIs for raytracing will at some point enable support for AMD's Radeon RX 6000 RDNA 2 graphics cards but that remains to be seen. We could also see a drastic difference between NVIDIA's RTX & AMD's own raytracing implementation in the same titles too. Following is a list of all the games available that are based on Microsoft's DXR API:

  • Battlefield V
  • Call of Duty: Modern Warfare
  • Control
  • Deliver Us The Moon
  • Dirt 5
  • Far Cry 6
  • Fortnite
  • Godfall
  • Metro Exodus
  • The Rift Breaker
  • Shadow of The Tomb Raider
  • Wolfenstein Youngblood
  • World of Warcraft Shadowlands

AMD themselves is targetting 1440P 60+ FPS performance in several AAA raytracing titles but it's not just games that will take advantage of AMD's RA cores. Content creators can also leverage the full potential of AMD's hardware-acceleration for ray-tracing in several applications such as Maya, Houdini, Blender, and AMD's own Radeon PreRender (with additional plug-ins). With RA cores, the performance improvement is seen all the way up to 68% over the Radeon VII graphics card which relies on a software-accelerated technique.

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AMD RDNA 2 Mesh Shading

First up, we have a new Mesh Shading pipeline that works in tandem with GPU compute. Mesh Shaders allow AMD to reveal more detail in the game environments through advanced culling & work creation.

AMD RDNA 2 Sampler Feedback

The sample feedback pipeline allows advanced data streaming and allows RDNA 2 to move beyond traditional memory limitations, allowing for richly defined worlds.

AMD RDNA 2 Variable Rate Shading

Variable-rate shading allows the hardware to focus the rendering work where it is most needed to deliver the most important visual cues in an image.

AMD RDNA 2 variable-rate shading functionality is built throughout the entire pixel pipe. With supported shading rates of 1x 1,2 .x 1,1x 2, and 2 x 2,AMD RDNA 2 provides usability and flexibility for developers.

The AMD RDNA 2 variable-rate shading functionality allows for a unique shading rate to be selected for every 8 x 8 region of pixels. This very fine granularity enables developers to make better decisions as to the right shading rate for a given region.

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