DataCenterChill synthesis · Based on the primary source listed below
Google has released a cooling design called Brazos that answers the most common objection to liquid cooling in an existing building: the pipework. Brazos is a sidecar rack that stands next to an IT rack. Liquid picks up heat from the chips, carries it a few feet into the sidecar, and gives it up to the air through heat exchangers, which vent into the hot aisle the room already has. The building's water system is never touched.
That matters because the alternative is a construction project. Running chilled water to every row of an operating hall takes months and a capital budget, and the racks in question cannot wait. Google's argument is that Brazos can go in one rack at a time, in any hall with enough power and normal air handling, which turns a facility upgrade into a delivery.
The reason any of this is necessary is the power of a single chip. Google notes that current AI and high-performance computing processors routinely pass 1,000 watts each, which is past the point where moving air over a heatsink can keep up. Reported figures put Brazos at roughly 60 kW of cooling per rack, against the 10 to 20 kW a legacy air-cooled rack was built for, using the Open Compute Project's ORv3 rack format.
There is a real trade-off, and it is worth stating plainly because the design does not hide it. The heat still ends up in the room. Brazos changes where it is captured, not where the building finally rejects it, so the hall's air handling has to be able to absorb the load and the hot aisle gets hotter. A site short on air handling capacity gains less than the rack number suggests.
Google says the design is generally available, that its manufacturing partners are ready to build it for others, and that the specifications and design principles will be published through the Open Compute Project in the coming months. Until those documents appear, the details available are the ones Google has chosen to describe.