AMD Helios (partial co-design): AMD revealed the TH6 scale up switch design publicly for the first time. If you look close enough, you can spot all the Broadcom ethernet retimers next to the flyover cables coming from the backplane into the switch ASIC. This design demonstrates AMD's lack of complete silicon product portfolio, particularly a scale up switch, which is necessary for a scale up rack. In the case of Helios, AMD relies on Broadcom for the scale up switch and retimers alone the scale up path. In the future, AMD are also working with UALink switch vendors in their pursuit of a true UALink scale up system. https://www.broadcom.com/products/ethernet-connectivity/phy-and-poe/optical/bcm83361.

In our advancing AI 2026 article, we talked about the challenges with these retimers and flyover cables towards manufacturing and signal performance. The retimers also add extra latency alone the scale up path. https://open.substack.com/pub/semianalysis/p/can-amd-break-the-cuda-moat-amd-advancing?r=2tvhp5&selection=49db110a-6f59-4bae-91a7-2492a088fac3&utm_campaign=post-share-selection&utm_medium=web&aspectRatio=instagram&textColor=%23ffffff&bgImage=true