I would avoid using 120mm fans, you don't need static pressure with case fans, what matters is cfm. The cm 690 iii is one of those cases that can take 3 200mm fans, so i would buy 2 extra MegaFlow 200 fans and put one on the side as an intake and one on top as an exhaust. More cfm for allot less noise. I would also buy a filter for the side fan though.