Dry Aging steak

stike

your fridge is already below 40, or your other food would spoil.

below 38 is better.  there is no worry at all about opening and closing the fridge door if you do it in the 'family fridge'.  but it is better to have a dedicated fridge, because you can crank temps lower (without worrying about veggies freezing, for ex.), low 30's is best, plus you don't have to worry about the fat picking up other food odors.

just get a regular fridge thermometer and toss it on a shelf.  maybe 5 or 7 bucks at bed/bath/beyond type places.

above 34 is not quite true.  meat won't really freeze solid at 32... but yeah, keep it cold.  colder you go, the slower the enzyme action, but also the slower any potential microbial action too (bacteria).