It can be quite loud. I am unsure as to the case fan settings. I may investigate when I get home from work but it can be quite loud at first. Graphics fan I set around 34% and it is barely audible over other fans while idling, when running a game I will have sound on and will up the fan to 40% maybe a bit higher and it will start to be fairly prominant.
I am however going to move the tower to the floor to the side of my desk. This way it will shield the noise a bit when playing games and I reckon this will reduce the noise quite significantly to where I sit at my desk. Not much louder than your average system though and it won't be a problem when its moved.