Doubtful that this is using traditional per-device water cooling. I’m betting that this is traditional hot row/cold row cooling and there is an evaporative component of the HVAC coolant loop to reduce the power requirements of the system as a whole.

Lemmy loves to shit on MS but they are constantly innovating in efficient data centers because spending less to operate directly reduces their expenditures, which directly equals profit on a service with fixed costs and multi-year reservations like Azure.

You can bet that if the solution was as simple as what you suggest that they would have been doing it for years, but the thermal considerations for one machine and the thermal considerations for 100,000 machines are not the same. The #1 priority to operate that many systems is to use as little power as possible because power is not only the biggest expense but also the primary limiting factor on the total number of systems you can host.