To add to the previous comments, a general rule of thumb is that larger fans tend to be more quiet than smaller fans, since smaller fans have to turn faster to move a given amount of air. I would avoid 80 mm fans, and generally speaking 140 mm fans are preferable to 120 mm fans.
One of the best available CPU coolers, in terms of both cooling effectiveness and noise performance (even when used without the low noise adapter it is supplied with), is the following one made by Noctua, which uses a 140 mm fan:
https://www.newegg.com/noctua-nh-d15s/p/N82E16835608072 However a relatively wide case is required to accommodate the height of this cooler.
I used that cooler in a computer I built last year, with the following case which includes two 140 mm fans in front and another 140 mm fan in the rear:
https://www.newegg.com/black-corsair-graphite-series-atx-full-tower/p/N82E16811139054 I built that computer for editing of 4K video material, among other things, so the CPU, graphics card, power supply, etc. that I chose are overkill for audio-related purposes by a large margin, but nevertheless it is very quiet. I don't know, though, if its relatively large size would be suitable for your purposes.
Also, keep in mind that for tasks that are relatively unchallenging for a computer, such as processing of audio material, it may very well not be necessary to connect all of the fans that are provided in a given case.
Good luck. Regards,
-- Al