# How to tell if fan is taking in air or exhausting?



## OrbitzXT (Dec 30, 2011)

I want to install a couple 120mm fans in my case, but I don't really know which way to install them to get air flowing in the direction I want. How do I tell which way I should be installing it?


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## fullinfusion (Dec 30, 2011)

Your not serious?


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## digibucc (Dec 30, 2011)

power it up quickly and put your hand in front of it. generally whatever side the company name/sticker/logo is on, but i don't know if that's a reliable rule of thumb.


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## JATownes (Dec 30, 2011)

The rule of thumb I always use is that the side with the frame on it is exhaust.  I believe that is universal.







^^This would be the exhaust side.


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## OrbitzXT (Dec 30, 2011)

Thanks to the two helpful posts. Should I be taking in air from the side door and exhausting through the back?


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## JATownes (Dec 30, 2011)

It really depends.  If you are putting the fans on the side door in front of the video cards I have tested and had two different results depending on the GPUs in at the time.  If your GPUs exhaust air out the back of the card, I would make the side panel fans intake to feed fresh air to the GPUs.  If your GPUs just bleed heat off in the case, I would make the side panel fans exhaust to get the heat out of the case.  That is my 2 cents.


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## OrbitzXT (Dec 30, 2011)

I have a GTX 590, it exhausts out the back but even at 100% isn't the strongest exhaust I've felt compared to some previous cards I've used.


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## JATownes (Dec 30, 2011)

Is the card bleeding off a lot of heat into the case?  I would probably test both ways (intake then exhaust) and see what gives you the best temps.


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## fullinfusion (Dec 30, 2011)

OrbitzXT said:


> Thanks to the two helpful posts. Should I be taking in air from the side door and exhausting through the back?


Really I would have helped but I thought it was a joke!


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## mediasorcerer (Dec 30, 2011)

Heat rises, so i vent my case -cold air in from the bottom, hot air out the top, if that makes sense,[or helps]
Quite often there is an arrow on the fan that indicates the direction of airflow too btw.


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## qubit (Dec 30, 2011)

OrbitzXT said:


> I want to install a couple 120mm fans in my case, but I don't really know which way to install them to get air flowing in the direction I want. How do I tell which way I should be installing it?



Yeah, I'm sorry dude, the answer is so obvious, that I'm not surprised some thought you were kidding, lol.  Anyway, I'd like to add to the helpful answers, here. You can tell:

- Apply power and put your hand in front of it. One side it will obviously be blowing and pushing your hand away. The other side will be doing the opposite and will suck your hand in. Of course, be careful not to allow your fingers to snag in the fan blades, as that can damage your hand and the blades

- Most, if not all, have two little arrows embossed on the outside edge of the frame, at 90 degrees to each other. These indicate the direction of rotation and air flow.

- EDIT: and what Depth said, below. Very obvious indication

I think an equally important question is about balancing the thrust from the front fan and the others in the case. I believe that the should all be the same, in order to avoid creating high and low pressure spots inside the case. I'm not 100% sure on this, so I'd be grateful if someone could clarify.

And finally, what do I do? I run my PC 100% of the time with the side panel off, so the only case fan I have running is the front one for the hard discs.


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## Depth (Dec 30, 2011)

I usually just look at the curvature of the blades. Think of a skewed aircraft wing and you get the idea.






Another sign is that the blades are bent forward, cutting "into" the air. This picture already posted by JATownes for example. It rotates clockwise with the tips cutting through the air like a scoop.


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## micropage7 (Dec 30, 2011)

OrbitzXT said:


> Thanks to the two helpful posts. Should I be taking in air from the side door and exhausting through the back?



side fan usually used to cold the whole board coz the flow straight to the board
the back usually for exhaust, so the intake is from front and side the exhaust from back or the top


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## Irony (Dec 30, 2011)

I have mine set up so that it sucks air in through the front and side and exhausts through the top and back. 

How did you manage to successfully build your rig in the first place not knowing witch way fans blow? or even be a member here for 4 years and not pick up on that... no offense. I'm kindof genuinely wondering.


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## digibucc (Dec 31, 2011)

the part you are missing: TPU _is_ Orbitz' brain. He doesn't have to know anything because he knows where to find the answer 
jk...we do seem to do his job for him pretty often  but that's ok


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## OneMoar (Dec 31, 2011)

or you just take a look at the side of it and the little arrows will tell you ^>

..... some people should't be allowed near pc's .. I think the op might be one of them......


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## xxdozer32 (Dec 31, 2011)

i just put a piece of paper in front of the fan, itll either suck it and get stuck or itll blow it way...


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## OneMoar (Dec 31, 2011)

http://www.youtube.com/watch?v=v4fU0Ajo4RM


....... wow people ....


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