Case Fans: Even Intake and Exhaust

I'm going to have one 120mm intake fan in the rear, which rates at 80 cfm. And I will have 3 80mm exhaust fans, which, combined will have around 83 cfm. Is it correct to calculate it this way and will the 3 cfm make it too uneven(I wouldnt think it would.)

Also, I'm gonna have the 120mm intake in the rear, while there will be 2 exhasts in the front and 1 in the top. Does that configuration sound like it will work efficiently?

 

Hmmm i aint very good with cases, but i would thing so, sucking in at the back, cool air goes through, warm air comes out the front, its a sham you cant have a fan at the side almost level with the CPU cooler, then your getting air directly from outside the air been blown straight at the fan.

Maybe if your case is on stilts or somthing, have a fan sucking out at the bottom, and fans at the front and back sucking in, that might work good.

With my other case, i had 2 fans on the rear side of the case, they were sucking in, one blown air onto the graphics card, the other blown air at the CPU cooler, i also has a fan at the back sucking in too, then one at the front sucking out, what i did was used incent sticks to see the airflow, i dont think the smoke will do any damage just to see what the airflow is like

 

No, the back panel fan should always exhaust. Hot air rises, so you pull cold air in the bottom front and exhaust it throught the PSU, back panel, and a blowhole if you have one. Also, as a general rule, you want more exhaust power than intake power. Balancing the intake and exhaust is really a non issue, as long as you can pull the hot air off the CPU then you should be fine.

 

CPU fans suck in, so its good if there is a fan sucking air from outside straight onto the CPU.

 

Yes, it is, but it isn't a must. Ducts that funnel air to the CPU fan are fairly common in cases nowadays.

 

Yea and there loud too, one of my neighbours has a mesh computer, and the ducting on that makes the pc really loud.

 

Yes, my case has an air duct on the side that is right above the CPU. I forgot about the PSU fan. Then should I have the two front and one top fan be intake fans, while the 120mm rear be used as exhaust?

 

No, put the 2 front as intake, the one on top exhaust, and the rear fan exhaust. You ALWAYS want fans on top exhausting, always.

 

I dont think the area of the fans is the best way to calculate the way air flows through your system. ie Theres nothing saying a 120mm fan will move twice as much air as a 60mm fan. (yeah, I know 60mm arne't standard)

I personally have two intake 80mm fans on the front, one on the side and 2 80mm exhausts on the back plus the psu exhaust. Works really well, the case never goes above 25c. So in my case ive got even intake/exhaust.

I couldnt say whether intake is better than exhaust or not, I suppose it depends on the temperature difference.

 

If you have to cool down a particular area like CPU then a intake fan in front of it will be the best idea. However, putting two fans(One for intake and other for exhaust) increases the speed of air flow...Speed will increase further with more fans and if you put them logically like everybody says that exhaust on the top and intake at the bottom....thats the best idea and make use of fans more efficient.

 

OK I've figured it out. I'm going to put two intakes in the front and one in the side and one exhaust in the back and on top. That should even it out along with the PSU exhaust. Scratch the 120mm. Are 5 case fans too much? Does anyone else have this many?

 

I have just 1 for Processor........Other than that, in my PSU hanging outside my CPU has 2 fans, which I will not count in my system..~!

 

I would keep the 120 mm, it will be quieter and move more air than the 80. Also, there is no such thing as too many case fans, your only limit is your hearing. My current computer has 2 case fans but the CPU cooler has 2 ultra high-speed 92 mm fans on it, each one moving about 100 CFM. If your ears can take it you would put fans in every concievable location.

 

Yeah, I agree. Its down to what your happy listening to!

All in all ive got 7 fans, plus 1 on the northbridge and a 3 fan hdd cooler which arent that noisey.

Incidently this comp im on now only has 2 fans plus the cpu fan and its just as noisey, they are the cheapest fans I could get so I suppose im paying the price now.

 

So, if you should always have fans exhausting on the back, and sucking in on the front, how would you go about doing that then on a case like mine were there is no vent on the front, only a comp system for the temps.

At moment on my case, on the back, a fan is sucking in, exatly the same level at the cpu cooler, then on the side i have a case fan bang in the middle of the side window, thats almost on the same level as the cpu and the rear, and thats sucking out.

My hdd gets air straightr from outside lol, i took floppy cover off and pushed hdd so its level with the front of the case.

 

Well, the fan on the side whould intake and the fan on the back should exhaust.

 

Why does it have to be the back seen as there both the same level, i dont see why it HAS to be the back :s

 

Well, what is the arrangement of your HSF? How is your fan oriented?

 

well it sucks air in....

 

... Well I see it is stock. I think the stock AMD fan intakes air form the side of the HS opposite the motherboard:

>> deontes airflow

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F >>------|
A >>------|
N >>------|
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If that is the case then the fan on the side would intake and blow air directly into the fan. Then, when the air blows out of the side of the HS it will be exhausted out of the case bay the rear fan and the PSU.