Despite the Xbox Series X's ray tracing being considered the "ultimate in realism," Microsoft is not too keen on it. In a Hot Chips deep dive on the AMD-powered GPUs at the heart of the next-generation console, Mark Grossman, Microsoft's principal architect, details the graphics silicon inside the Series X and what role ray tracing plays in it. is discussed in detail.

The short answer seems to be "not much."

GPU dual-compute units (DCUs), such as the Xbox Series X's Big Navi, have dedicated hardware to accelerate the real-time ray tracing process. However, this appears to be the only change in RDNA 2.0 dual compute units compared to the first-generation ones found on AMD RX 5700 series cards.

There are 26 dual compute units (i.e., 52 actual individual compute units), but a high-level look at the GPU structure shows that pairs of DCUs appear to be disabled on each chip. Overall, AMD GPUs have 56 compute units built in, and with such a large slice of 7nm silicon, it may make sense to have some redundancy there.

Since the next generation Xbox GPU is built for DirectX 12 Ultimate and thus uses the DirectX Raytracing API, the dedicated hardware blocks of the AMD GPU are the same as Nvidia's RTX-based graphics cards Bounding Volume Hierarchy (BVH) algorithm, which will be aimed at accelerating the Bounding Volume Hierarchy (BVH) algorithm.

"We will add hardware built into the compute unit to perform ray intersections with the acceleration structures that represent the geometry hierarchy of the scene," says Grossman. This is a significant portion of the specialized ray tracing workload, and the rest can be performed with baseline shader and memory design with high quality and good real-time performance"

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"The overall raytracing speed gains vary widely, but for this task, the performance can be 10 times better than a pure shader-based implementation.

However, while Microsoft is indeed working with AMD to ensure that there is some support for ray tracing inside the Xbox Series X GPUs, Grossman does not seem so enthusiastic about how readily it can be exploited [17

"For ultimate realism, we support DirectX Raytracing acceleration. We wanted to balance the die resources dedicated to the two technologies, since ray tracing can be selectively applied depending on the material and environment."

Maybe he is presenting to a screen because of an unknown number of virtual attendees sitting on the other side, or maybe he really doesn't think real-time ray tracing will be of interest to developers for generations to come. Either way, we would like to give him a big hug.