Thursday, October 29th, 2020 Posted by Jim Thacker

AMD unveils Radeon RX 6000 Series GPUs

AMD has unveiled the Radeon RX 6900 XT, the Radeon RX 6800 XT and the Radeon RX 6800: the first three GPUs in its new Radeon RX 6000 Series of gaming cards, based on its new RDNA 2 architecture.

The firm is positioning the three ‘Big Navi’ cards, which are due to ship worldwide in November and December, as direct competitors to Nvidia’s current GeForce RTX 30 Series of Ampere-based GPUs.

Although we don’t traditionally cover gaming GPUs on CG Channel, the new RX 6000 Series cards have a number of features interesting for CG artists: notably, dedicated ray tracing accelerator cores.

AMD Radeon RX 6000 Series GPU specifications
RX 6900 XT RX 6800 XT RX 6800 RX 5700 XT
Architecture RDNA 2 RDNA 2 RDNA 2 RDNA
Process 7nm 7nm 7nm 7nm
Stream processors 5,120 4,608 3,840 2,560
Compute units 80 72 60 40
Game clock (GHz)* 2.0 2.0 1.8 1.8
Boost clock (GHz) 2.3 2.3 2.1 1.9
Compute performance
FP32 (Tflops)
23.0 20.7 16.2 9.8
GPU memory 16GB
Ray Accelerators? Yes Yes Yes No
TBP 300W 300W 250W 225W
Release date December 2020 November 2020 November 2020 July 2019
MSRP $999 $649 $579 $399

*AMD’s specs for the RX 6000 Series omit base clock speed in favour of the higher expected in-game speed.

How do the key specs compare to Nvidia’s current GeForce RTX GPUs?
Above, you can see key specs for the new cards, and one of their predecessors: 2019’s RX 5700 XT.

In its own benchmarks, AMD compares the Radeon RX 6900 XT to Nvidia’s GeForce RTX 3090, the RX 6800 XT to the RTX 3080, and the RX 6800 to the last-gen RTX 2080 Ti, standing in for the unreleased RTX 3070.

In terms of core specs, the Radeon RX 6000 Series cards trade blows with the Nvidia RTX 30 Series cards they are pitched against, offering higher boost clock speeds but lower FP32 compute performance.

Both price and power consumption, in the form of Total Board Power (TBP), are in AMD’s favour in the case of the two higher-end pairs of cards; in Nvidia’s favour for the Radeon RX 6800 and GeForce RTX 3070.

And at 16GB apiece, the on-board memory capacity of the Radeon RX 6000 Series cards is lower than that of the GeForce RTX 3090, but higher than that of the GeForce RTX 3080 and 3070.

New dedicated Ray Accelerators for GPU ray tracing – in game-like renderers, at least
We won’t go into the details of the Radeon RX 6000 Series cards’ new RDNA 2 architecture here. (If you’re interested, Anandtech has a thorough analysis.)

However, it has one feature of particular interest to CG artists: like Nvidia’s RTX cards, but unlike AMD’s previous Radeon RX GPUs, the RX 6000 Series feature dedicated ray tracing cores.

Each of the cards’ compute units now comes with a “high performance, fixed-function Ray Accelerator engine” for hardware-accelerated ray tracing, analogous to the RT cores on Nvidia RTX cards.

Software can access the Ray Accelerators via DirectX 12’s DXR (DirectX Raytracing) API.

While DXR is used to accelerate ray tracing in games – and in game engines commonly used for CG work, including Unreal Engine and Unity – it’s less widely used by traditional DCC applications.

Currently, most offline renderers that support hardware-accelerated ray tracing access the RT cores on RTX cards via Nvidia’s own OptiX API, as is the case with V-Ray and Blender’s Cycles renderer.

As a result, unless you use Unreal Engine for rendering, you’re unlikely to be able to make use of AMD’s new Ray Accelerators to speed up your CG work when the Radeon RX 6000 Series cards first ship.

It will be interesting to see whether more DCC applications start to support DXR for GPU ray tracing in future.

One interesting part of AMD’s strategy here is FidelityFX, an open-source developer toolkit for implementing hybrid rendering pipelines by selectively adding ray traced effects to rasterised renders.

Although it’s pitched primarily at game devs, it’s also the approach that AMD has been taking in its own DCC tools, including the ‘full spectrum rendering‘ system in its Radeon ProRender renderer.

Pricing and shipping dates
AMD’s RX 6800 and Radeon RX 6800 XT should become available worldwide on 18 November 2020, with recommended prices of $579 and $649.

The RX 6900 XT should follow on 8 December 2020 with a recommended price of $999.

Read more about the Radeon RX 6000 Series GPUs on AMD’s website