When Nvidia launched Turing, it decided to bifurcate the brand of its product by dividing the GeForce brand into two segments. GTX cards, even those based on Turing-class GPUs, do not include new specialized hardware features that support Nvidia ray tracing. RTX cards, which support Microsoft DirectX ray tracing with some additional hardware capabilities, would do so.
Last month, the company changed this direction. DXR / RTX Capabilities would have unlocked on Nvidia GTX GPUs, including latest generation Pascal cards, via a special driver update. But Nvidia's early discussions on DXR also pointed out that the impact of ray traceability on performance was ruinous – heavy enough that only special cards like Turing could handle it. The new WHQL 425.31 driver enables RTX GPUs on GTX.
The ray tracing has a lot of performance, but the results of the Pascal card tests with this feature suggest that at least the 1080 Ti is able to activate it from time to time. Nvidia has published the results of its own tests in three games: Metro Exodus, Battlefield V and Shadow of the Tomb Raider.
At 1920 × 1080, the GeForce GTX 1080 Ti is capable of maintaining frame rates higher than 50 fps in two of the three titles when the quality is lower than "Ultra". In the third game, Metro Exodus, only the 1080 Ti can crack 30 frames per second in this mode.
The relatively strong results for the 1080 and even the 1070, however, suggest that GTX players should at least be able to sample games in ray tracing mode. Even the GTX 1060 can exceed 30 fps in Battlefield V. For those looking for independent results, PC Gamer has confirmed that its own numbers are largely consistent with those of Nvidia.
Note that these results do not include frame durations, which have generally increased on Turing GPUs during DXR calculations. It is possible that Pascal does not work as well as a Turing GPU with similar pace. Without information on the time frame, we can not draw any conclusion in one way or another.
It is unclear whether Nvidia's decision to open support for GTX cards has implications for AMD's ability to support these features. The fact that both cards support a common code path does not always mean that their implementations of a feature do not benefit from accurate tuning. The entire DXR support setting may have been done only on Nvidia GPUs. Therefore, the operation of AMD cards in these workloads or with these features is still unknown.