It's power cannot be silenced!
More seriously it depends on a heck of a lot of factors including your PS4. Your room could just be hotter than mine on average for example - hotter room = hotter console = more chance of fans kicking in more often and more noticeably.
All I can say is mine is mostly quiet unless it's been hammered for many hours and the room is hot in which case the fans do kick in noticeably (although not enough to really matter much) so it's either your PS4, the conditions in which you use it (orientation, ventilation, room heat, room ventilation) or a combination of both.
More seriously it depends on a heck of a lot of factors including your PS4. Your room could just be hotter than mine on average for example - hotter room = hotter console = more chance of fans kicking in more often and more noticeably.
All I can say is mine is mostly quiet unless it's been hammered for many hours and the room is hot in which case the fans do kick in noticeably (although not enough to really matter much) so it's either your PS4, the conditions in which you use it (orientation, ventilation, room heat, room ventilation) or a combination of both.