Is top dust filter needed for corsair 270r?

[Arviee]

Guys, what do you think, is top dust filter required to keep the dust out in stock fan configuration(1 front intake, 1 rear exhaust, both 120mm)?

What about if I also add 1 front intake?

I assumed the hot air will try to rise and leave the case through the top thus keeping the dust out, but I'm not sure if this will happen in practice. Fwiw cpu cooler is also air, so it should add some air circulation (?).

 

[CountMike]

Only intake fans may need dust protection, on exhausts they are just hindrance to air flow.

 

[Arviee]

Would you advice to put 2nd intake fan or leave it stock? I'm asking because I saw thermal test for 275r (I have 270r) and 2nd intake fan actually increased temps. I wonder if it's the same case for my... ughh, case (I was unable to find thermal tests for diff. fan setups for 270r)?

 

[CountMike]

Well, yes, let temperatures be final judge and yes, wrong fan, in wrong place or turned wrong way can be a hindrance to cooling.