Basically just the CPU fan, case, and PSU (if you're lucky). If someone can figure out how to get Doom running on just those 3 things, young people will be able to ascend.
Well....sure but there's people who reviee coolers with a decibel reader so they can equalize noise level when testing.
Imo though air cooling is still louder than water cooling. I have both and while i appreciate thaf air colling is great too today and probably peace of mind, but a nice rgb liquid aio is also not expensive these days....specially compared to what the other PC parts cost now...