Power Distribution Board

Overview

The Power Distribution Board (PDB) is the power conversion and distribution component within an AI rack compute tray. It converts 48V busbar input to the supply voltages required by GPUs, CPUs, and IO subsystems. PDB design is a key differentiator between AI rack ODM implementations: isolating the PDB from the compute motherboard protects expensive GPU/CPU hardware from power subsystem failures and simplifies field replacement.

In QCT's GB200 rack engineering, the PDB architecture changed significantly from the first generation: the GH200 system used a 1.3 kW PDB (125mm × 160mm) that split 48V across two separate paths — one to GPU/CPU and one to IO. The GB200 system consolidated to a single 8 kW centralized PDB (124mm × 146mm) delivering 12V to all components, achieving higher power density in a slightly smaller footprint. The architectural shift to a single, isolated board ensures that any PDB failure does not risk the more expensive compute motherboard.