AMD Helios Physical Architecture
A single Helios rack packs in a massive amount of hardware, and unsurprisingly, the rack itself is similarly massive. AMD used the Open Rack Wide specification here, which is a double-wide rack standard 120cm wide, twice the width of OCP’s ORv3 specification (and itself a bit wider than the classic 19-inch rack). Meanwhile, AMD has fully populated the 44OU tall rack with compute nodes, switch trays, and power shelves, putting every inch of Helios to good use.
Overall, the system is built around 18 compute trays. Each one houses a single 96-core EPYC Venice socket SP7 CPU, which in turn is paired with a quartet of MI455X GPUs.
The compute trays, in turn, are wired together using 6 switch trays. While not visible from the front of the rack, there are 4 cable cartridges that serve as the physical backbone of the scale-up network.
Finally, power for the system is provided by a 50 Volt busbar, mirroring the broader industry trend towards busbars for rackmount servers. As with other vendors, busbars simplify assembly and maintenance by streamlining power delivery to each rack while reducing cable clutter.
For that matter, the liquid cooling system in Helios follows a similar philosophy. With virtually every aspect of Helios liquid-cooled (including the aforementioned busbar), AMD is relying on blind-mate quick-disconnect connectors to allow components to be easily added and removed from the system. According to AMD, the system requires a coolant flow rate of 385 liters per minute, which in turn will be needed to remove up to 245kW of heat.
Next, let us get into the AMD EPYC Venice and MI455X compute tray.
