if you can fit the 120mm in front then do it, and leave the other 80 where it is, or best scenario (and quieter) is replace the 80's with 120's so all are 120mm
as a general rule of thumb though, front bottom and side intake, top and rear exhaust
Got it. Should I move the top exhaust fan close to the rear exhaust fan or leave it as is? The reason I ask is it's right beside the cpu fan.