Are you serious?
Whats the point of a FILTER on a rear fan, it just stops 50% of the airflow and causes noise
In case you havent noticed I have had this case a while, temps have risen about 1-2c since removing it and I have a quieter replacement on the way... I do know what I am doing.
Oh and look, my northbridge fan is unplugged and it isnt a passive heatsink! Oh noes... long as it is stable and quiet I couldnt care less.