Supermicro SYS-A21GE-NBRT (B200, air-cooled)
8 × B200 per node, with 8 compute rails at 400G. That is 3.2 Tb/s of scale-out network per node.
- GPUs per node8 × B200
- Compute rails8 × 400G
- Scale-out bandwidth3.2 Tb/s
- Storage links2 × 400G
- In-band links2 × 100G
- BMC ports1
- Rack units10U
- Typical power14 kW
- Maximum power14.5 kW
What this means for the fabric
8 compute NICs means 8 rails. In a rail-optimized design each of those rails is sized on its own against the node count, then multiplied back up, so the leaf tier is driven by the rail count and not by the total endpoint count.
Storage and in-band management are separate fabrics with their own switches and their own optics, and the 1 BMC port per node feed the out-of-band network, which also has to carry every switch and every PDU in the cluster.
Power and racks
At 14 kW typical draw, this node fills a rack's power budget long before it fills the space. A 45 kW rack takes 3 of them on power alone, against 4 on rack units. Power is what actually sets the rack count.
Notes
Air-cooled HGX B200. The 10U form factor is the cost of air cooling at Blackwell power levels — compare against the 4U liquid-cooled variant for rack count.
Source: Supermicro HGX B200 10U air-cooled system documentation. Needs verification