# [SOLVED] In need of Airflow Advice



## ajcc323 (Dec 31, 2010)

Which is a better setup for case airflow?

Setup #1:
High RPM Intakes and Low RPM Exhaust.

Setup #2:
Low RPM Intakes and High RPM Exhaust.

*The Low RPM fans are factory fans that came with the case itself - it can't go any higher.
While the High RPM ones are bought separately.

Not sure if RPM matters (with enough fans for cooling) but I do know that a positive static pressure is best.
The more intakes, the better.

My current is setup is #2 with 4 Intake fans and 3 Exhaust fans. 

Thanks in advance!


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## GZ (Jan 31, 2010)

*Re: In need of Airflow Advice*

The RPM doesn't matter as much as the CFM.

For example, an 80mm fan at 3200RPM will have less CFM than a 120mm fan @ 2000RPM.

It is always best to have negative pressure inside a case (i.e. More air being pushed out of the case). The reason for this is to draw fresh air in through the case vents.

Could you post each fan and configuration including your PSU model?

Example;


```
120mm Antec Tri-Cool High setting - exhaust
92mm Cooler Master - front intake
120mm Cooler Master - side intake
Corsair 640TX
```


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## ajcc323 (Dec 31, 2010)

*Re: In need of Airflow Advice*

Hey Gavinzach,

Here are the details on the fans and PSU:

120mm Rosewill (Pre-installed Case Fan) (x2) - Front Intake
120mm Rosewill (Pre-installed Rear Case Fan moved to Front Drive Bay Panel Optional Feature) (x1) - Front Drive Bay Intake
120mm Rosewill (Pre-installed Case Fan) (x1) - Side Panel Intake
120mm Antec Kuhler 620 CPU Liquid Cooling System (Thermally Controlled - PWM) (x1) - Rear Exhaust
120mm Rosewill RFA120BL (x2) - Top Exhaust
Antec EarthWatts 750W 80 Plus Certified


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## ajcc323 (Dec 31, 2010)

*Re: In need of Airflow Advice*



gavinzach said:


> The RPM doesn't matter as much as the CFM.
> 
> It is always best to have negative pressure inside a case (i.e. More air being pushed out of the case). The reason for this is to draw fresh air in through the case vents.
> 
> [/CODE]


I see, I've been browsing through different forums about positive and negative static pressure and alot so far agreed that positive is the best to have on your system as it minimizes dust build-up and pushes air out from all ventilations forcefully.


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## GZ (Jan 31, 2010)

*Re: In need of Airflow Advice*

I have read alot of that hubris as well.

Positive pressure creates eddys inside your case and pockets of warm air. It will not limit dust buildup either, it just forces all the dust that enters your system in through one point.

The most important aspect is the airflow. The more cool air you can move through the case the more heat will be removed.

As a general rule of thumb, exhaust fans should be located at the back/top of the case and intake fans should be located at the bottom/front of the case. If your case has a side fan for expansion slot cooling, it could be either way, each case is different but in most applications, a side fan at low RPM over the video card will keep the GPU cooler and not adversely affect airflow.


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## greenbrucelee (Apr 24, 2007)

*Re: In need of Airflow Advice*

what he said ^

Basically if you have a side fan blowing air in and fron/bottom fam blowing air in and only one exhaust fan effectivley what you get is a akin to a small tornado inside your system where one area will have a lot of dust build up and heat generated whilst the rest of the system is ok.

I have antec 1200 case with 3 120mm fans at the front a 200mm fan at the top and 2 120mm fans at the back. The front fans are intake whilsts the rest are exhausts. I have the option of a side fan but this would cause the issue I described above so there is no need.

Also good cable management can increase airflow and cooling by 5% even the odd cable in the way of airflow can effect your cooling.


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## ajcc323 (Dec 31, 2010)

*Re: In need of Airflow Advice*

So in summary:

+ Negative static pressure
+ Low RPM side fan

Should the intake fans have a higher CFM? or the exhaust fans?


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## gcavan (Aug 13, 2009)

*Re: In need of Airflow Advice*

It generally always takes a bit of experimentation to find the best fan set-up for your particular situation. The best starting point for most is one or more high flow exhaust fans in the upper rear and a low volume intake on the lower front pulling cool air across your hard drives. 

I don't subscribe to any negative/positive pressure theory. I simply aim for a good front to back air flow and add spot cooling if necessary


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## greenbrucelee (Apr 24, 2007)

*Re: In need of Airflow Advice*



gcavan said:


> It generally always takes a bit of experimentation to find the best fan set-up for your particular situation. The best starting point for most is one or more high flow exhaust fans in the upper rear and a low volume intake on the lower front pulling cool air across your hard drives.
> 
> I don't subscribe to any negative/positive pressure theory. I simply aim for a good front to back air flow and add spot cooling if necessary


Me too. All my fans have the same CFM and I use antec tri cool fans and a tuniq tower as the cpu cooler.


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## ajcc323 (Dec 31, 2010)

*Re: In need of Airflow Advice*

Thanks guys, I appreciate your thoughts on the matter.


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