4 fans

D

DREW10

Weaksauce
Joined
Aug 4, 2004
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90
Im planning on building a computer case in the near future and im deciding how many fans i wantand what size.....

if I have 4 80 mm fans(2 pulling, 2 pushing) rated at 30 cfm in a 1 cubic foot case. would I multiply the number of fans by the cfm(4x30) to find the total cfm? or is it just 30 cfm no matter how many fans you have?
 
I would think you multiply it by 2, because of the direction of the airflow, the internal CFM in the case will only be 60. As long as you're building a computer case, I would urge you to go with 120mm fans. They are quieter, much more efficient at moving air (blade area to motor cylinder size ratio is bigger), or if you don't care about the noise you can get ~100 CFM per fan!
 
yeah im thinking of using 4 120s on and a fan controller.........i was just using 80 mm as an example
 
Assuming all the numbers you listed were just examples, you would have 60cfm of air flowing through, i.e. in a 1 cubic foot case the air inside gets replaced ~once a second :eek: You might be moving 120cfm of air (4x30) but there is only 60cfm flowing through your case (2x30 intake, 2x30 exhaust)

And yes, definitely go with 120mm fans.
 
waddles said:
Assuming all the numbers you listed were just examples, you would have 60cfm of air flowing through, i.e. in a 1 cubic foot case the air inside gets replaced ~once a second :eek: You might be moving 120cfm of air (4x30) but there is only 60cfm flowing through your case (2x30 intake, 2x30 exhaust)

And yes, definitely go with 120mm fans.
Click to expand...

yeah....but it gets better. 4 120 mm fans with 80 cfm each, that means 160 cfm. then the air gets replaced 2.66 times a second.......now thats AWESOME..........
 
You must keep in mind that you will almost never achieve the rated flow rate due to case obstructions and such.
 
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