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Ampere vs Turing real time ray tracing overhead

At the Ampere announcement stream NVidia CEO Jensen Huang made several bold claims regarding their new line of GPUs, the RTX 3000 series. Such claims include that the new microarchitecture, compared to Turing, “doubles ray triangle intersection throughput”, “Ampere’s RT Core delivers 58 RT teraflops compared to Turing’s 34”, “Ampere is an incredible two times the performance and energy efficiency of Turing.”, “Ampere RT Cores doubles ray-intersection processing.”, and of course the one that stuck on most enthusiasts heads “3080 is twice the performance of 2080 at the same price”.

With actual independent reviews out while the RTX 3080 represents indeed a significant performance increase over the last generation, few of NVidia’s claims actually turned out to be true in a vacuum. Of particular interest is the performance overhead when turning ray tracing “on” in games that support it. In Turing we saw for instance that Metro Exodus at 4K Ultra Quality would drop from 92 FPS to a barely playable 37 FPS with RT turned on using the 2080ti (without a significant improvement to image quality it should be said). Has this overhead been mitigated with NVidia’s new architectural improvements in Ampere?

4K Overhead

4K real time ray tracing results

Using data from Hardware Unboxed’s excellent analysis we see that while ray tracing performance has indeed improved, the overhead really hasn’t changed much at 4K, about 6% on average. In Metro Exodus there is in fact a slightly higher overhead resulting in you losing 4% more frames when compared to the 2080ti. A far cry from Jensen Huang’s claims. Wolfenstein Huangblood represents the best case scenario here with the RTX 3080 losing 16% less frames when turing real time ray tracing compared to the RTX 2080ti.

1440p Overhead

1440p real time ray tracing results

At 1440p we see more reasonable improvements as far as performance overhead is concerned with the 3080 losing 13% less frames when turning ray tracing on compared to the 2080ti, on average. Strangely, Metro Exodus now represents the greatest improvement at 35% less frames lost while Control maintains roughly the same overhead with a mere 2% improvement. Perhaps the 10GB of VRAM are responsible for the lackluster performance at 4K but we will have to wait for the 3090 results to be sure.

Conclusion

It’s clear that while the NVidia 3000 series represent not only an impressive jump in performance on every level considering we’re at the end of Moore’s Law, but also a return to good value for money (in the case of the 3080 at least) it seems the company did themselves a disfavor by over promising double the performance versus Turing.

Real time ray tracing still represents a massive performance overhead and the improvements in visual fidelity are suspect and subjective, rather than bringing you “joy beyond gaming” as Jensen Huang suggests. Perhaps this will change with upcoming AAA titles such as Cyberpunk 2077 and Vampire: The Masquerade – Bloodlines 2 supporting the technology.

While Ampere is a return to form by Nvidia, the RTRT overhead is still far from being mitigated, especially at higher resolutions.

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