Some systems use liquid cooling for the GPU and CPU, but air cooling for the PSU, RAM and SSDs.

With that said, by the standards of industrial sites data centres are quiet, low traffic and smell free. An industrial area that can’t build a data centre certainly can’t build a steelworks or oil refinery or leather tannery.

They almost certainly need fans on the outside of the building to cool the 55C water back down to 45C. But correct, no fans on the servers themselves or even in the building. Except perhaps for the humans, so they can stand to work inside the building, when needed.

The humming are the gas turbines which also damages your health.

If the outdoor temperature is cool enough (maybe 30C?), you just pipe the liquid outside through a large enough loop or heat exchanger to get it back down to under 45C. Even better if you can put the loop in a lake and dump the heat there (maybe not better from an ecological POV though). The pumps moving all that liquid becomes the noisiest component.