So as the title suggests, my case currently has negative pressure within the case so it's pulling in dust at a not-so-awesome rate. While the standard answer is "add more intake fans", I'd like the best way to do that without messing with the airflow direction of my case. I'm currently using a Corsair Carbide Series Air 540 with the default setup of included case fans, which are 2x 140mm intake and 1x 140mm exhaust. http://www.newegg.com/Product/Product.aspx?Item=N82E16811139022 I can fit either 2x 140mm or 3x 120mm in the front, 2x 140mm or 2x 120mm up top, and 1x 140mm or 1x120mm in the back. My question to you guys is this: should I replace the two front 140mm fans for three 120mm fans, or just add intake or exhaust fans to the top of my case?