Do data centers use single phase or 3 phase to power their infrastructure?
We were offered 120V or 208V at at one US data center, so three phase is available.
Six pulse rectifiers are efficient at making DC, but powerful DC circuits are hard to manage once you exceed the working voltage of your typical arc welder.
Ordinary switched mode power supplies start with rectifier followed by a a power-factor correction circuit,  these will run just fine from DC of a similar voltage
By feeding DC you eliminate mist of the losses in the PFC and reduce losses in the input filter capacitors. This might be the difference between 95% and 96% efficiency