NVIDIA Releases DirectX Raytracing Driver for GTX Cards; Posts Trio of DXR Demos

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Last month at GDC 2019, NVIDIA revealed that they would finally be enabling public support for DirectX Raytracing on non-RTX cards. Long baked into the DXR specification itself – which is designed encourage ray tracing hardware development while also allowing it to be implemented via traditional compute shaders – the addition of DXR support in cards without hardware support for it is a small but important step in the deployment of the API and its underlying technology. At the time of their announcement, NVIDIA announced that this driver would be released in April, and now this morning, NVIDIA is releasing the new driver.

As we covered in last month’s initial announcement of the driver, this has been something of a long time coming for NVIDIA. The initial development of DXR and the first DXR demos (including the Star Wars Reflections demo) were all handled on cards without hardware RT acceleration; in particular NVIDIA Volta-based video cards. Microsoft used their own fallback layer for a time, but for the public release it was going to be up to GPU manufacturers to provide support, including their own fallback layer. So we have been expecting the release of this driver in some form for quite some time.

Of course, the elephant in the room in enabling DXR on cards without RT hardware is what it will do for performance – or perhaps the lack thereof. High-quality RT features already bog down NVIDIA’s best RTX cards that do have the hardware for the task, never mind their non-RTX cards, which are all either older (GeForce 10 series) or lower-tier (GeForce 16 series) than the flagship GeForce 20 series cards. This actually has NVIDIA a bit worried – they don’t want someone with a GTX 1060 turning on Ultra mode in Battlefield V and wondering why it’s taking seconds per frame – so the company has been on a campaign both at GDC and ahead of the driver’s launch to better explain the different types of common RT effects, and why some RT effects are more expensive than others.

The long and short of it being that simple reflections and shadows can be had without terrible performance drops on cards that lack RT hardware, however the more rays an effect requires, the worse the performance hit gets (or perhaps, the better an RTX card would look). So particularly impressive effects like RT global illumination and accurate ambient occlusion are out, however cheap reflections (which are always a crowd pleaser) are more attainable.

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