@viciousviscosity It is funny how one becomes attuned to the machine environment. I once spent most of a year in a server room (including sleeping there) courtesy of the German military and I was able to hear - and feel -if any of the machines wasn't running right straight across the whole room.
At one job in the early naughties, I was famed for escorting a salesperson and a few prospective customers into my (ok, the company's, but mine) datacenter, stopping dead, and saying "Something's wrong."
Nineteen racks of gear, and we had... an extra beep.
But we got the deal, so; all good.
Generalistic and moderated instance.