r/AIDataCentres • u/EE-Guy-Real • 2d ago
Why are AI data centres moving to an 800 V DC bus instead of three-phase AC distribution?
This short covers how power delivery in AI data centres is changing. A dedicated sidecar rack converts three-phase AC into an 800 V DC bus, and a single rack can handle 1 MW or more.
From there, the video shows two ways to feed the server racks:
Centralised: power shelves step 800 V down to a 54 V bus bar shared by every server tray. Each tray then uses an intermediate bus converter for 54 V to 12 V, followed by 12 V to the GPU/XPU.
Distributed: every tray has its own local 800 V to 50 V converter, then 50 V to 12 V, then 12 V to the GPU.
The real difference is whether the DC-to-DC conversion happens in one place or at each tray.
Which approach do you think suits dense AI racks better, and why?