RT Performance Deep Dive: RX 6800 XT vs RTX 3080

[Wrinkly]

No surprises, but gives better understanding to those looking to buy in to next gen cards.

And in an attempt to pull some heads out of the sand, if not something else ...

Fast forward to 33:30 for number one.

 

[Grim5]

This about sums up the video in a few seconds

The ray accelerator units in the RDNA2 CU performs Ray-Box and Ray-Triangle Intersection checks -- the same as the RT Cores do in Ampere. However, Ampere's RT cores, also accelerate BVH Traversal Algorithms -- whereas in RDNA 2 this is done via the compute shaders using SIMD 32 units.

And for denoising, Ampere is using Tensor Cores, But on RDNA2, it's using it's compute shaders.

That's why RDNA2 is much slower.

 

[Gregster]

Watched the first vid and interesting. RT is clearly heavy on performance, which is to be expected but quite a bit heavier on the AMD side. Re-Bar (I think it is called) will hopefully help with that though and bring the field more level.

 

[eeii]

I would also add an AMD gpu using an Nvidia code path for de noiseing is never going to be a fair representation.

 

[Rroff]

This about sums up the video in a few seconds

I'm not sure anything (game wise) is actually using the Tensor cores currently for denoising - though they are faster than shaders for that they are also harder to use in something like a game due to how they need to be utilised to not result in a performance penalty.

 

[Wrinkly]

The big one would have to be Dirt 5 since that is the title used to defend AMD's RT performance.

Additional frame time in ms for RT

            6800XT  3080
RT Medium      3.1   1.2
RT Ultra       1.8   0.7

Lower is better!

 

[Grim5]

I also found it interesting how the performance changes on the type of feature used in the RT - for example RDNA2 seems reasonable adept at doing RT Shadows, but not so when it comes to global illumination, reflections and depth of field.

Its unfortunate though that RT Shadows is the least impressive RT effect that can be used and one which I just leave disabled generally