800 VDC Power Distribution

Overview

800 VDC power distribution is a high-voltage DC architecture developed to address the physical limits of 50 VDC at AI rack power densities above 250 kW. At 1 MW rack load, 50 VDC requires 20,000 A bus bar currents—electrically impractical; 800 VDC reduces this current by 16×. The architecture was co-developed by Delta, NVIDIA, Meta, Microsoft, and Google and moves all power conversion outside the IT rack into an external in-row power rack or sidecar, since AI racks are 75% occupied by compute payload.

The transition plan follows three phases: (1) an in-row power rack with 800-to-50 V DCDC converters for existing 50 V servers at loads above 250 kW; (2) 800 V native servers with on-tray converters, eliminating the intermediate conversion step; and (3) a solid-state transformer (3–6 MW) converting medium-voltage AC directly to 800 VDC for building-scale distribution with integrated renewable energy sources.

The 800 V power shelf accepts true three-phase AC without neutral, producing either 800 V or floating ±400 V (Diablo-400 compatible), available in 19-inch (106 kW, 4 PSU) and 21-inch (180 kW, 6 PSU) form factors. Outputs aggregate on a three-conductor DC bus bar (positive, negative, ground) into a DC PDU with remote-controlled fuses, providing four cross-link cable outputs to IT racks. The DC-to-DC converter in the IT rack delivers 108 kW in 1U at 50 V—three times the density of prior HPR shelf designs. The long-term 800 VDC architecture directly couples fuel cells, solar, wind, and centralized battery storage, supporting carbon neutrality in gigawatt-scale AI data centers.