The only reason I can tell it's on, is the very quiet hum of the slow speed water pump. Large fans run at 1200rpm and are fully quiet.
I have over a meter of radiators there.
Fun fact, I bought my first rtx3090 4 years ago. A year ago I bought another one and they are still the same price used.
I may buy another one (for my servers)
If you are that locked in to Apple, its pretty easy to buy a used Mac Mini older gen for all the non AI stuff.
But this is a discussion about inference. Buying a Mac anything for any sort of local inference is a COLOSSAL waste of money.