Try to stop your PSU fan when te system is on, if you haven't done that already. Also, see if the harddrive cage makes a lot of vibration. If so, the system noise might be caused by harddrive vibration.
I think you can start by replacing the 212+ fan...and you can also get rid of all +140mm fan, big 200mm fan are sometimes not that silent :/
Edit : if fan speed is 1000rpm, start by reducing it
Check the bios to see if there are some options to do that.
Agreed, even very good fans and well regarded fans need to be run at about 500-800 rpm in order to be quiet.