Help with case and Fan Setup

[dream3]

Hey guys!
 

How are you all doing?

 

I just got my corsair obsidian 350d case here and I need some help regarding its fans.

 

At the moment I have 2x120mm apache blacks in the front as intake and one in the rear as exhaust.

Top grills are closed with dust filer foam. CPU cooler is a noctua so I want the air stream to be front to back AND I want positive pressure.

 

I'm thinking about getting 2x140mm noctua fans for the front so more air can be blown towards the GPU, which is already too close to the PSU.

 

However, in that case, should I upgrade the rear fan as well? Or the bigger the difference between CFMs, the better? 

 

For instance, with the 2 new noctuas I'll be getting in theory more 36 CFM intake, while the exhaust CFM will still be 56 from that one apache. So 140 CFM intake vs 56 CFM exhaust.

I'm just not quite sure if positive pressure is best if the intake CFM is close to the exhaust CFM or the other way around: the more intake CFM the better while keeping exhaust to a minimum.

 

Thanks!

[WoodenMarker]

The CFM difference doesn't mean much for cooling and it's not that easy to extrapolate cooling effectiveness from the cfm spec alone. Restrictions or lack thereof around the fans will impact how they perform. 

For cooling effectiveness, more and larger fans will perform better. 

Adding a top exhaust if you don't already have one will probably make a bigger difference than swapping out the front fans though.