Intel Details its Ray Tracing Architecture, Posts RT Performance Numbers


Intel on Thursday posted an article that dives deep into the ray tracing architecture of its Arc “Alchemist” GPUs, which are particularly relevant with performance-segment parts such as the Arc A770, which competes with the NVIDIA GeForce RTX 3060. In the article, Intel posted ray tracing performance numbers that put it at-par with, or faster than the RTX 3060, which which it has traditional raster performance parity. In theory, this would make Intel’s ray tracing tech superior to that of AMD RDNA2, because while the AMD chips have raster performance parity, their ray tracing performance do not tend to be at par with NVIDIA parts at a price-segment level.

The Arc “Alchemist” GPUs meet the DirectX 12 Ultimate feature-set, and its ray tracing engine supports DXR 1.0, DXR 1.1, and Vulkan RT APIs. The Xe Core is the indivisible subunit of the GPU, and packs its main number-crunching machinery. Each Xe Core features a Thread Sorting Unit (TSU), and a Ray Tracing Unit (RTU). The TSU is responsible for scheduling work among the Xe Core and RTU, and is the core of Intel’s “secret sauce.” Each RTU has two ray traversal pipelines (fixed function hardware tasked with calculating ray intersections with intersections/BVH. The RTU can calculate 12 box intersections per cycle, 1 triangle intersection per cycle, and features a dedicated cache for BVH data.

The TSU, as we said, is the secret sauce of Intel’s ray tracing performance. It’s key to achieving what Intel calls “Asynchronous Ray Tracing.” The TSU organizes ray tracing instructions and data such that rays with similar hit shaders are optimally allocated unified shader resources of the Xe cores, for the best possible allocation of hardware resources. The slide above details the ray tracing pipeline, where the TSU is shown playing a big role in optimizing things for the hit-shader execution stage.

Intel posted performance numbers for the Arc A770 at 1080p, compared with the RTX 3060 at the same resolution, across a selection of 17 games. These include Ghostwire Tokyo, which was earlier found to be extremely sub-optimal on the “Alchemist” architecture, but has since been optimized for in the latest beta drivers. The A770 trades blows with the RTX 3060, even if there are a few cases where the NVIDIA chip is slightly ahead. This is certainly a better showing when compared to a Radeon RX 6650 XT pitted against the RTX 3060 in ray tracing.

The A770 isn’t meant for 1440p + Ray Tracing (nor is the RTX 3060), but performance enhancements like the XeSS and DLSS make both possible. While Intel didn’t compare the A770+XeSS to RTX 3060+DLSS at 1440p, it posted a slide about how XeSS makes gaming with ray tracing more than playable at 1440p, across both its “balanced” and “performance” presets.

Below is the video presentation from Intel:


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