Better Without Exhaust Fans?

[Elfear]

I've been pondering on this lately and I'm hoping you guys have some answers. My case currently has three 120mm intake fans that push 103cfm each at full tilt. I usually keep them at 5-7V for silence but I imagine that's still pushing quite a bit of cfm. I have three exhaust fans, two 80mm on the back of my case and one slow 120mm in my PSU. The two 80s I have push 75cfm at 12V but I usually keep them at a more conservative 5-7V.

My question is are the two 80mm fans limiting the amount of air that can escape the case? Would I be better off removing them so the air can flow freely?

 

[thecoolnessrune]

I think your fine as long as air in = air out. Try to prevent negative or positive pressure. If all you have is exhaust fans, try putting something in the front to equalize it.

 

[Elfear]

Originally posted by: thecoolnessrune
I think your fine as long as air in = air out. Try to prevent negative or positive pressure. If all you have is exhaust fans, try putting something in the front to equalize it.

Well that's what worries me. Intake cfm = 300cfm and exhaust cfm = 200cfm at most. Just thinking the 80mm exhaust fans are creating a big bottleneck. I do have a hole in the top of the case to vent air out of but I don't know if it's sufficient.

 

[Zepper]

Most cases have a lot of places for air to escape so unless you go to the trouble that I do to create a positive pressure condition in your case, it's almost impossible to get it accidentally - perhaps with both of your 120mm intakes at full speed...

.bh.

 

[IdaGno]

You may find the info here helpful.

So, how exactly do you get a positive coefficient? The obvious solution is to get a load of intakes and zero exhaust. But that solution isn?t going to net you anything except a very dusty case. In order to get good airflow - note, flow - you need to have both an intake and an exhaust, but working in different magnitudes. As an example, a 120mm intake and a 80mm exhaust is a very good way to pump case pressure to a stable positive.

 

[imported_Seer]

Why don't you run a couple tests yourself and tell us how it turns out?

 

[Elfear]

Originally posted by: IdaGno
You may find the info here helpful.

So, how exactly do you get a positive coefficient? The obvious solution is to get a load of intakes and zero exhaust. But that solution isn?t going to net you anything except a very dusty case. In order to get good airflow - note, flow - you need to have both an intake and an exhaust, but working in different magnitudes. As an example, a 120mm intake and a 80mm exhaust is a very good way to pump case pressure to a stable positive.

Interesting. Thanks for the post. Sounds like I'm probably ok.

Originally posted by: Seer
Why don't you run a couple tests yourself and tell us how it turns out?

I might just do that and see what happens. Maybe this weekend, time permitting.