As part of the Hot Chips 2020 event, Microsoft spoke in more detail about the architecture of the next generation Xbox Series X game console. The company also showed for the first time what a block diagram of the chip looks like and its embodiment in silicon, on the basis of which the new game console works.
Recall that the console is based on a System-on-Chip (SoC) developed by AMD and manufactured using an improved 7-nm process technology from TSMC. Equipped with eight AMD Zen 2 cores and 16 virtual threads, the total area of the SoC is 360.4 mm2…
In addition, the chip is equipped with 52 active computing units (Compute Units) of the graphics subsystem based on the new AMD RDNA2 architecture. It is also expected to form the basis for new graphics cards in the desktop segment of the Radeon Navi 2X series.
The set-top box processor has 15.3 billion transistors on board, which is 1.7 billion more than the NVDIA Turing TU104 graphics chip. The area of the latter is 545 mm2, and it is produced according to the norms of the 12-nm technological process. The density of the transistors in the new AMD crystal has more than doubled compared to the chip in the Xbox One X console (its area is 367 mm2), which has only 6.6 billion transistors.
Microsoft confirmed as part of the presentation that the full die uses 26 Dual Compute Units (DCUs). Thus, she disabled two DCUs (4 CUs) for the final product. It was previously stated that the graphics subsystem uses 56 CU.
According to resource calculations Tom’s Hardware, the graphics core occupies approximately 47.5% of the total SoC area. Microsoft also announced that RDNA2 graphics do have dedicated Ray Accelerators. They will be responsible for either processing four textures or four raytracing operations per clock.
Unfortunately, the company did not provide a comparable performance metric for ray tracing (DXR) technology. Instead, the Xbox Series X is estimated at 380 billion operations per second when calculating ray intersections with boxes and 96 billion operations per second when calculating intersections with triangles. For example, the same NVIDIA claims for its flagship gaming video card GeForce RTX 2080Ti performance at the level of 11 gigabytes in ray tracing. For the upcoming new NVIDIA video cards based on the Ampere architecture, this value is likely to be even higher.
According to Microsoft, as DirectX12 Ultimate-enabled hardware products become more popular, DXR technology will increasingly appear in new games. As the resource notes VideoCardz, Microsoft’s approach to the use of ray tracing technology is not much different from the purpose for which it is currently used by NVIDIA in its video cards. The technology is not intended to replace rendering, but to complement it, increasing the visual saturation and image fidelity while using resources wisely. Microsoft itself describes DXR as “a cost-effective enhancement to traditional rendering.”
It is currently unknown if Microsoft is using additional hardware to accelerate machine learning, as NVIDIA is doing with its DLSS 2.0, which uses tensor kernels. However, the slides do mention Machine Learning. According to the Tom’s Hardware resource, it uses INT4 and INT8 computation formats based on the use of stream processors.
During the presentation, the company also focused on the difficulties of producing new-generation crystals. Not only have manufacturing costs increased, but so have the complexity of the microprocessors themselves. According to Microsoft, the answer to this question is the development of new and patented technologies. The slide titled “GPU Evolution” shows that since 2013, Xbox game consoles have received an almost 10-fold increase in performance in terms of the number of Gflops per TDP value (however, the company did not provide the TDP values themselves).
Microsoft recalled that the Xbox Series X will support HDMI 2.1 output, allowing for refresh rates of up to 120fps at 4K resolution and even up to 8K at 60fps. The console does not have a DisplayPort output.
The set-top box video encoder / decoder supports 4K and 8K video decoding in AVC and HEVC / VP9 formats, and also has support for AVC (H.264) and HEVC (H.265) codecs. This will make life easier for those who want to stream their gaming adventures better.
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