Making Haf 912 quieter?

[JustBen]

Hello

The fans in my case are quite noisey, it doesn't bother me but the mrs is winging so could do with replacing the fans with something quieter.
Any suggestions? Do i need to buy specific ones for the case or just any the same size?

 

[Hakanese]

Case fans come in a variety of specs and sizes, what you're after is fans with a low sound rating in decibels (db), and a good airflow rating.
What fans do you have in the case at present? I know your case has the option to swap out teh smaller 120mm fans for 200mm fans