Going from 40mm fans to 80mm fans will not take energy usage from 25% to 1-2%. They must have taken an extreme example to compare against. What they’re doing is cool, but this is a marketing exaggeration targeted at people who aren’t familiar with the space.

Oxide also isn’t the only vendor using form factors other than 1U or focusing on high density configurations. Using DC power distribution is also an increasingly common technique.

To be honest, a lot of this feels like Apple-esque marketing where they show incredible performance improvements, but the baseline used is something arbitrary.

It's just plain old engineering, optimized to sell whole racks not individual servers or <=8U units, sprinkled with opinions about low-level firmware etc, with a bespoke OS and management stack.