4U LIQUID-COOLED REFERENCE SERVER
A 4U liquid-cooled server with eight NVIDIA H100 GPUs on one HGX board: the building block of Colossus’s racks.
Supermicro’s 4U liquid-cooled GPU server holds an NVIDIA HGX board with eight H100 GPUs linked by NVLink and NVSwitch, plus two Intel Xeon host CPUs and 32 memory slots. Cold plates on the chips carry heat into a liquid loop.
The Supermicro and ServeTheHome case study of December 2024 describes xAI using this 4U Universal GPU system in Colossus. The model here follows Supermicro’s reference datasheet and manual; the exact deployed SKU is not published.
Eight of these servers and a coolant distribution unit make one Colossus rack of 64 GPUs. The server is where GPUs meet the CPUs, network adapters and liquid cooling they depend on, the role the GB300 compute tray plays in newer NVIDIA racks.
Supermicro · SYS-421GE-TNHR2-LCC datasheetSupermicro / ServeTheHome · xAI Colossus case study, December 2024Sources reviewed October 28, 2026
Opening the 3D model…
CONNECT THE SCALES
Separate host and HGX trays follow the reference service manual; not a verified deployed SKU or exact board layout. Exploded spacing is illustrative.
Revision 1.0a; retrieved October 28, 2026 · Figures 1-1, 1-3, 1-5 and 1-6 (pages 10, 13, 15–16)
Reference front/rear panels and separate host/HGX trays. This does not establish the deployed Colossus SKU.
Retrieved October 28, 2026 · Page 1, enclosure and interconnect
449 × 174 × 895.35 mm reference enclosure. Exact deployed SKU and internal placement are not established; H100 configuration selected.
December 2024 · Pages 2–5 (rack/cooling), 7–8 (network)
Sponsored tour of the Supermicro portion. Interior photos on page 3 are an SC23 prototype, not an opened deployed server.
March 22, 2022 · Figure 1 and H100 SXM5 configuration
One GH100 compute die, five enabled HBM3 stacks; schematic layers and connection paths.
Original authored geometry. No private CAD, exact facility floor plan, performance simulation, or current deployment total is implied. Cooling and networking lines show relationships, not surveyed routes.