# Which Case Fans Take Air In/Out?



## Alpha_Blob (Apr 26, 2011)

Hey everyone,
I would love if you could tell me how I know which fans on the case take air in and which take air out and if I can/need to control that 
Also, how do I know if the fan I am going to buy is a good fan? Do I need to check for RPM or for loudness or something? Please help me I have no clue about Fans whatsoever 
And btw, I connected my fans to the motherboard and not to the PSU 
Thanks already,
Alpha_Blob


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## Motoxrdude (Apr 27, 2011)

Usuaully you want to orient the fans to work with the natural flow of air (hot air rises) so the fans towards the top of the case are exhuast and the fans on the bottom are intakes. With fans, the RPMs don't really matter. What you want to look for is the CFM (how much air the fan moves) and dB (how loud the fan is). IMO anything under 25dB is quite enough, but if you want a silent case try and stay under 20dB.


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## Nanobyte (Apr 27, 2011)

The other general rule is air in at the front, out at the back.  If you don't have front case fans, the rear fan and the PSU fan suck in air through the case/front and out the back to provide some cooling for the HDDs and DVD drives.


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## Alpha_Blob (Apr 27, 2011)

Motoxrdude said:


> Usuaully you want to orient the fans to work with the natural flow of air (hot air rises) so the fans towards the top of the case are exhuast and the fans on the bottom are intakes. With fans, the RPMs don't really matter. What you want to look for is the CFM (how much air the fan moves) and dB (how loud the fan is). IMO anything under 25dB is quite enough, but if you want a silent case try and stay under 20dB.



Thanks 
And can you tell me a good company for case fans. I know that Cooler Master's MegaFlow 200mm fans seem to be great fans (I need to check the info you gave me though  ) but I mean generally a case fan production company 
Also, the higher the CFM the better, right? And from what number of CFM upwards (or downwards) is it good?
Thanks again and hoping that you reply again soon 
**EDIT**Hey I have one more question: You said i want to orient the fans to work with the natural flow of air, does that mean that if Side A faces outwards it will take air in and if Side B faces outwards it will blow air out? Thanks  **EDIT**
Alpha_Blob


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## Alpha_Blob (Apr 27, 2011)

Nanobyte said:


> The other general rule is air in at the front, out at the back.  If you don't have front case fans, the rear fan and the PSU fan suck in air through the case/front and out the back to provide some cooling for the HDDs and DVD drives.



Thanks man 
I already have case fans, but I want them to look cooler so I want to buy LED fans 
Alpha_Blob


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## PixelVandalism (Apr 27, 2011)

Alpha_Blob said:


> Thanks man
> I already have case fans, but I want them to look cooler so I want to buy LED fans
> Alpha_Blob



Just check what way the fan pushes by plugging it into the psu and turning it on, then just put it in the way you need it to go


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## Alpha_Blob (Apr 27, 2011)

PixelVandalism said:


> Just check what way the fan pushes by plugging it into the psu and turning it on, then just put it in the way you need it to go



Haha you quoted the wrong thing but thanks for the answer 
That is a great idea 
Thanks,
Alpha_Blob
*
I have one more question for everyone please *
Since I can only plug in 4 fans (excluding the CPU Heatsync Fan) to the Motherboard, and if I buy all the fans I want to I will have 7 inside my case rolleyes which ones should I plug into the motherboard and which ones into the PSU.
Please help haha 
Alpha_Blob


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## cabinfever1977 (Apr 27, 2011)

I plug in the fans closest to the plugs on the motherboard to the board and the ones farther away or the ones i dont need to know the speed there running at, i plug into the power supply.


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## Alpha_Blob (Apr 27, 2011)

cabinfever1977 said:


> I plug in the fans closest to the plugs on the motherboard to the board and the ones farther away or the ones i dont need to know the speed there running at, i plug into the power supply.



Haha ok, but I meant which ones do I/do I not need to know the fan speed of?


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## PixelVandalism (Apr 28, 2011)

You don't really need to know the speeds of any fans other than the cpu cooler, so it's up to you, I have 4 case fan's and they are all on low, they're all dual speed, but you should be fine plugging in what you can where you can.


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## mihir (Apr 28, 2011)

Depends.If you do not care about the noise of the fans then plug all of them to the PSU and if yu like your computer to stay quiet then plug the noisy ones to the motherboard and the quiet ones to the PSU.


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## scbjmshpv (Apr 28, 2011)

majority of cases have hard drive bay in the bottom and optical drive on top, as they are put under desk by major PC user, so the front fan takes air in and the back fan takes air out which is higher than front fan.

connecting fans to mobo is great solution as it lets you control the speed if you want via hardware monitor software, once i learned that i never bought 4 power pin fan.


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## Motoxrdude (Apr 28, 2011)

Alpha_Blob said:


> Haha ok, but I meant which ones do I/do I not need to know the fan speed of?



It doesn't really matter to be honest. The only one I would for sure plug into the motherboard is the CPU fan. Some motherboards support a fan controller so you can adjust the speed of the fan. As long as the fans are quite though their really isn't a point though.

As far as the brands go, it doesn't really matter. I would just stick to fans with a a lot of positive reviews.


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## Alpha_Blob (Apr 28, 2011)

PixelVandalism said:


> You don't really need to know the speeds of any fans other than the cpu cooler, so it's up to you, I have 4 case fan's and they are all on low, they're all dual speed, but you should be fine plugging in what you can where you can.



Ok thanks 
It's just that I heard that the PSU plugged in fans always run at top speed while the Mobo plugged in fans vary and are controllable if the user wishes 
Anyway I'll just plug randomly and hope everything works.

Thanks for everyones help


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