case fans.

[Curioisman]

So I have asus gt301 case which comes whit 4 preinstalled fans, 3 in front, 1 in back and I got 2 more fans for top, so basiclly I've tried to a research what CFM the preinstalled fans are but out of luck, I want to create a slightly positive or near balanced airflow, the 2 fans on top are 44,37 CFM. So the question is, is there a way somehow to check the CFM of fans without being a rocket scientist?

[Bombastinator]

41 minutes ago, Curioisman said:

So I have asus gt301 case which comes whit 4 preinstalled fans, 3 in front, 1 in back and I got 2 more fans for top, so basiclly I've tried to a research what CFM the preinstalled fans are but out of luck, I want to create a slightly positive or near balanced airflow, the 2 fans on top are 44,37 CFM. So the question is, is there a way somehow to check the CFM of fans without being a rocket scientist?

The way I know to check if a case is positive or negative is look for a crack that does NOT have a fan blowing on it and test whether air is moving in or out of the crack with a reallly small telltail, like a hair or a piece of a piece of yarn or a down pinfeather or something. Tiny, light, will move in the slightest airflow.  

[WoodenMarker]

The cfm listed in specs is for unobstructed airflow. In a case, obstructions like mesh or other objects lower the effective cfm. 

It may take some testing to find a good balance but you can just run your intakes at higher rpm than exhausts for positive airflow. 

[Curioisman]

20 hours ago, WoodenMarker said:

The cfm listed in specs is for unobstructed airflow. In a case, obstructions like mesh or other objects lower the effective cfm. 

It may take some testing to find a good balance but you can just run your intakes at higher rpm than exhausts for positive airflow. 

yea that was my original thought, but the intake fans are DC and i don't know their RPM, the exhausts are pwm so basicly I could run them at lower rpm just incase

[WoodenMarker]

5 hours ago, Curioisman said:

yea that was my original thought, but the intake fans are DC and i don't know their RPM, the exhausts are pwm so basicly I could run them at lower rpm just incase

What motherboard are you using? You should be able to read rpm from the fan headers. 

[Curioisman]

17 hours ago, WoodenMarker said:

What motherboard are you using? You should be able to read rpm from the fan headers. 

z390 pro4

[WoodenMarker]

2 hours ago, Curioisman said:

z390 pro4

There should be options for pwm/dc control and rpm readings in the bios. 

[Curioisman]

is this a too much of a positive airflow, chassis3 is intake chassis1 is exhaust

[Bombastinator]

10 minutes ago, Curioisman said:

is this a too much of a positive airflow, chassis3 is intake chassis1 is exhaust

I was once told that the best possible airflow is nearly exactly equal with just a bare whisper of positive. Following that negative airflow is often better.  Implies strong positive airflow is not good. That seems like more than a bare whisper just looking at the numbers.  Would depend on fan impedance though.  If you’ve got an AIO radiator in the chasis3 section net airflow may be less than implied. 

Edited August 28, 2021 by Bombastinator

[Curioisman]

43 minutes ago, Bombastinator said:

I was once told that the best possible airflow is nearly exactly equal with just a bare whisper of positive. Following that negative airflow is often better.  Implies strong positive airflow is not good. That seems like more than a bare whisper just looking at the numbers.  Would depend on fan impedance though.  If you’ve got an AIO radiator in the chasis3 section net airflow may be less than implied. 

this is the closest I got being 100% intake all the time and 81% exhaust