Top Exhaust instead of rear exhaust

[reno7]

Hello everyone, I'm planning on placing 3 140 mm fans on my case, 2 for intake and 1 for exhaust but I have an issue and id like your opinions. 

 

Problem is: the usual place for exhaust (next to the motherboard) only fits a 120mm fan so I wonder if I should place a 120 mm fan there or just place the 140 mm fan as a top exhaust fan and leave the back hole empty. 

 

See image below (not my actual case btw)

 

[Jack Dvorak]

could just do both. thats what i'm doing at least.

 

Personally I have 2x 140mm in front of my case, and 1x120 on the rear, and 1x120 on the top with a dust filter on the parts the fan doesn't cover.

[reno7]

3 minutes ago, Jack Dvorak said:

could just do both. thats what i'm doing at least.

 

Personally I have 2x 140mm in front of my case, and 1x120 on the rear, and 1x120 on the top with a dust filter on the parts the fan doesn't cover.

if I do 2 intake + 2 exhaust I would kinda have neutral pressure and the only reason I'm getting 3 fans is to have positive pressure to avoid dust build up, I only want 1 exhaust.

[WoodenMarker]

System specs?