Depends entirely on the type of CPU cooler you get, and the quality of the included case fans. I replaced the 120mm fans on my Hadron Air with Noctua fans because they were quieter, but the stock fans werent really loud - i just sit like 2ft from the computer. The cooler i linked in my original build (Zalman CNPS Quiet) is very, very quiet. It only becomes audible when the CPU is under full load and even then it is only a pleasant whir.
The GPU fans on my GTX 970 almost never even spin up and when they do they are not audible over the rest of the fans. At loudest, i get a pleasant humm.