# Which way do Fans blow?



## bcomatts

I am about to upgrade and add some fans to my system and I was wondering how it worked.  Fans like my CPU and Vid Card fan, do those blow toward the chip or do they take air away from the chip?  I tried sticking my hand infront of the chips but I can't tell where the air is coming from.

Furthermore, cases that have fans mounted on walls or top, is that like an exhaust system or is it actually sucking air in? like so: http://lib.store.yahoo.net/lib/xoxide/clear5.jpg

And on a regular computer with only the fans from the psu, cpu, vid card, the air comes in from where? and then gets flushed out the psu right?

Thanks, just trying to understand the air flow before I go upgrade/add fans.


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## Verve

Fans will always blow toward the chip. Usually only case fans will blow outward, taking the air out of the tower.


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## diduknowthat

well if you look on the fan, there usually are arrows pointing at the way the fan spins and the way air gets blown. 

On the computer on the link, I would guess that the two front fans are sucking, the one back is blowing out. The top is blowing out, and the two sides i'm not sure about.


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## Greggie Boy

Take for example my case: Aspire XNavigator...front fan sucking in, two rear fan blowing out, top exhaust, psu fans blowing out and large side fan blowing out. There is a big misconception that the side fan should be blowing"in" and some people change it because it will blow towards the cpu and "must be better"WRONG" The warm air has to be moved out,otherwise you're only moving warm air around. My cpu(Prescott) runs below 30c so go figure???


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## BrandonL

Another way to tell is to look at the fan and see where all the dust is collecting. The side that has the greater amount of dust on it can help you determind what way it spins. it's hard to explain but if u check it out you'll know what i mean.

if you happen to not have any dust on ur fans... well then idk lol


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## Yeti

> Fans will always blow toward the chip. Usually only case fans will blow outward, taking the air out of the tower.


Usually, but not always.


> Furthermore, cases that have fans mounted on walls or top, is that like an exhaust system or is it actually sucking air in?


Both, generally the setup is intake fans on the front/bottom and exhaust fans near the rear/top.


> There is a big misconception that the side fan should be blowing"in" and some people change it because it will blow towards the cpu and "must be better"WRONG" The warm air has to be moved out,otherwise you're only moving warm air around. My cpu(Prescott) runs below 30c so go figure???


That's kind of a case by case situation.  True, there are setups that will benefit from an exhaust side fan, but the opposite is also true.


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## BrandonL

I remember what you said about putting your hand in front of the fan to see which way the wind was going. If you couldn't feel the wind then either it's going into the computer or the fan is too slow and you need to clean it


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## s_m_w_d

why dont you check which way the fans are running in it now!  its the easiest way I could think off!yeti is right the fans on the rear are in alot of cases blowing out air! what are you trying to change around


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## BrandonL

he doesn't want the fans to make noise and someone else was giving him suggestions on getting smaller fans or removing ones that could be replaced by pipes... i think you should thoroughly examine the fans to make sure that there is nothing hitting against it and making the sound... or..... maybe the fan was installed backwards... try turning it the other way


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## Dilly man 2

is that your case? if so is that a sunbeam case? i have the same case but i can only fit 4fans + the psu fan...


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## BrandonL

i still dont understand why they need to put 5 fans in the cpu... there must be some type of alternative


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## Yeti

> i still dont understand why they need to put 5 fans in the cpu... there must be some type of alternative


 5 fans in the CPU?? Do you mean in the case?


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## BrandonL

umm yeh lol... oops.

now that i think about it, i only have 3 fans in my cpu


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## diduknowthat

BrandonL said:
			
		

> umm yeh lol... oops.
> 
> now that i think about it, i only have 3 fans in my cpu



3 fans on your cpu?? what heatsink do you have?


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## Chris Chan

lol I think he means case again.


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## BrandonL

i give up lol. i have at least 2 black spinny things in my system and that's all im gonna say. they look like fans and they spin like fans so i think they're fans

what's the different between a fan and a fancase?


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## Yeti

> what's the different between a fan and a fancase?


The "black spinny things" that are attached to your case are case fans - they bring in fresh air from and exhaust hot air to the air outside case.  You'll also have a fan on your CPU heat sink (HSF) and possibly on your video card heat sink.  The PSU will also generally have at least one fan exhausting.  That's pretty much it for basic fans.


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## BrandonL

o0o well in that case i have two case fans and one fan... there we go... that sound more accurate?


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## Yeti

> o0o well in that case i have two case fans and one fan... there we go... that sound more accurate?


Yes, yes it does


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## StrangleHold

Front- intake
Side- intake
Top- out take
Rear-out take


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## Archangel

StrangleHold said:
			
		

> Front- intake
> Side- intake
> Top- out take
> Rear-out take



depens on the grafics card, if you should make the front intake out exhaust


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## StrangleHold

Archangel said:
			
		

> depens on the grafics card, if you should make the front intake out exhaust



The front should never be a exhaust fan, the front fan is to pull  cool air in the bottom so the back fans pull hot air out no matter what video card you have, now the side fans can be tried either way to see which way is the coolest


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## Archangel

StrangleHold said:
			
		

> The front should never be a exhaust fan, the front fan is to pull  cool air in the bottom so the back fans pull hot air out no matter what video card you have, now the side fans can be tried either way to see which way is the coolest



o really?  well, i have my front fan as exhaust, because the heatsink + fan of my 6800GT is bolowing its hot air towards the front.
so,.. instead of blowing the hot air back into the case, i pull it out there imediately.  and, because of that, my 6800GT ( Oc'd to ultra ) is at 43*C idle.

so, i does matter what grafics card you have.


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## BrandonL

i have a question... when it comes to the fans, how would i clean then so that they take in/blow out more air? i've tried thoroughly rubbing the dust off with q-tips but it's not the best way. is there anything easier?


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## StrangleHold

BrandonL said:
			
		

> i have a question... when it comes to the fans, how would i clean then so that they take in/blow out more air? i've tried thoroughly rubbing the dust off with q-tips but it's not the best way. is there anything easier?



Old Tooth brush and a can of compressed Air works pretty good


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## StrangleHold

Archangel said:
			
		

> o really? well, i have my front fan as exhaust, because the heatsink + fan of my 6800GT is bolowing its hot air towards the front.
> so,.. instead of blowing the hot air back into the case, i pull it out there imediately. and, because of that, my 6800GT ( Oc'd to ultra ) is at 43*C idle.
> 
> so, i does matter what grafics card you have.



How is your video card and fan in a different place than everybody elses, I have built over 200 computers and never have I saw someone use the front fan as a exhaust, have you ever thought that using it as a intake would be blowing cool air to the card, heat rises!

 Bottom of page http://images.google.com/imgres?imgurl=http://www.heatsink-guide.com/airflow.gif&imgrefurl=http://www.heatsink-guide.com/case.shtml&h=584&w=530&sz=22&tbnid=I96N1WxE6aYJ:&tbnh=132&tbnw=119&hl=en&start=1&prev=/images%3Fq%3DCase%2BFan%2Bplacement%26svnum%3D10%26hl%3Den%26lr%3D%26sa%3DN


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## Archangel

have you ever seen the cooler on a 6800GT/ULTRA or the one on a 7800GT(X).. because, they are constructed to blow the hot air towards the front of the case. wich would make putting the front fan as exhaust a logical choise.

i think a oc'd xfx 6800GT running cooler as a non oc'd one with the front fan as intake is proof enough


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## StrangleHold

What ever you want to do!


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## BrandonL

where do you buy compressed air cans?


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## Archangel

StrangleHold said:
			
		

> What ever you want to do!



getting sarcastic now?    maybe you should get a bit deeper into the logic of my setup before saying its wrong..


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## Cromewell

You can get compressed air at most computer shops.


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## Lamilia

there are many ways to put the fans i think the best is probably the highest ones are outake and the lower ones are intake (also having an equal amount of intakes and outakes probably helps) because hot air rises so lower outake fans probably do nothing


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## BrandonL

okay that's good because i know of a couple shops near my house that probably have them because they are computer stores.

It doesn't matter if they are Macintosh stores though does it? a comp. store is a comp. store.


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## Cromewell

probably doesn't matter, but I haven't used a Mac since grade school so I don't know if they collect dust like PCs do.  A PC parts shop will have it for sure, not sure about a Mac shop.


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## BrandonL

well the macs that come with towers might have fans which may contain fan cases and fans so they might sell the air compressed cans there, but idk... it's a long shot.

lol since grade school huh? way back when


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## Archangel

well.. you can also use a vacuum cleaner with a brush on the front.
i have a old p2 here, wich runns since '98, and it has clean fans.
all myou have to do is hold the Fan so it cant turn because of the vacuum cleaner sucking air through it.

because then its rpm will go way to high, and the inductors in the motor will be teared apart.


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## Yeti

> because then its rpm will go way to high, and the inductors in the motor will be teared apart.


 but they're DC motors (though it still might help to hold the fan blades for cleaning purposes)


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## Archangel

Yeti said:
			
		

> but they're DC motors (though it still might help to hold the fan blades for cleaning purposes)



yes.. but a DC motor also works with L's you know.


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## Yeti

> yes.. but a DC motor also works with L's you know.


Agh, you're right... and you made me open my power conversion book that I never wanted to look at again


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## Cromewell

> lol since grade school huh? way back when


Joke all you want, it's been at least 10 years if not more


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## davie23223

*cpu fan*

Does the cpu fan blow into the heatsink or does it blow out of the heatsink?


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## Ku-sama

this is an openion, im switching my CPU and side fans to both exaust to see what happends


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## Mr.Suave

already been discussed
http://www.computerforum.com/showthread.php?t=26305


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## davie23223

Okay, I think I get it now.

cpu fan blows into the heatsink/chip.

The PSU counts as 1 exhaust.

Top and rear end of the case are exhaust fans.

Bottom front are intake fans.

the side case fans can be exhaust or intake fans.

My question is, Do you need equal exhaust/intake fans ie. 2 exhaust 2 intakes, or do you need more exhaust fans ie. 3 exhaust 1 intake, or more intakes ie. 3 intakes 1 exhaust.

And if the side case fan is an intake, wouldnt it blow into the cpu fan witch would cause a problem?


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## Praetor

Threads merged.


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## sid3wayz

well it all depends on the type of motherboard
http://vip.netsurf.ru/browse/?r=75042 these guyz shoul be able to give u some info on ur fans and other gear


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## Dilly man 2

i went front intake, back side and top exhaust.


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## fade2green514

depends on the heatsink, i have a heatsink that faces the back of my case. however i can tell you that whichever way the fan faces, it will always blow air through metallic fins. also, side fans blow inward, fans at the back of the case blow outward, and fans in the front of the case blow inward. that is the norm.


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## Greggie Boy

You want more exhaust than intake to get the warm air out. The opposite way would really defeat the purpose,lots of warm/hot air with nowhere to go(soundlike I,m describing myself) I have only one front intake,the top,two rear and large side fan are all exhaust an that's the way it was shipped(Aspire XNavigaor)


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## H_L

The only thing that will get damaged in a normal case fan when spinning at hi rpm is the oscillator circuit because its brushless when spinning at hi rpm it generates power forcing it back into the circuit, some fans have diodes inline the oscillator but extreme voltage will destroy it. 
Trust me my fan spins over 50,000 rpm (mod)

AND hot air rises so the exhaust fans are at top, (intake bottom) unless you have a weird setup


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## Timo

The ones on the side blow in against the graphic card and the rest of the mobo, the one in the back blows out as does the one in the top (blow out). If there are any on the front; they blow in.

DISCLAIMER: That would seem logic to me, if the top one blows in I would reverse it myself.


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