Top casefan type and size, help

[mikko.haranen]

So my case is the Phanteks 400s TG. I have two Noctua NF-F14 PWM fans as intake and one NF-S 120mm fan as exhaust at he rear. When gaming, the fan pushes out really warm air out is quite loud, so my question is, should i get another exhaust fan on top, and what size, and would it cause negative air pressure if i went with the 140mm exhaust on top, or should i just go for the120mm as exhaust? Or get a 140mm intake there. Im lost.

 

[Aeacus]

If you put only one 140mm fan at the top as exhaust then you'd still have positive pressure since you have 2x 140mm front intakes while 1x 140mm top and 1x 120mm rear exhaust fans.

But if you were to go with 2x 140mm at the top as exhaust then you're looking towards negative pressure, unless you run your intake fans much faster than your exhaust fans.