Microsoft already trialled this in Scotland, except it was powered by prototype tidal which was also being tested at that site.

One of the other things Microsoft tested was running the server room in a pure nitrogen atmosphere. Apparently this was very beneficial as it reduced the failure rate of components - you can’t have a spark without oxygen. That was actually the main advantage taken away from the test, with a view to maybe adopting that for datacentres on land (I doubt this though, the level of protection you’d need for workers makes it cost-prohibitive).

Cold is better managed by being somewhere cold - which is why they’re all busy building tons of datacentres in Nordic countries.