Which direction for rear case fan to face?

[Technique]

This morning i stripped the PC to clean out all the dust. The only problem is i can't remember which way the rear case fan was facing.

 

It is an Akasa fan. On one side is a foil akasa badge in the middle with nothing covering the fan blades.

 

On the other side is a red akasa badge in the middle with like 'spider' legs blocking (if you will) access to the blades. Also on this side is the wiring for the fan.

 

There are 2 arrows on the base of the fan. One points to the side corner where the wiring has been ran to & the other arrow points towards the side that has the 'spider legs' & the red Akasa badge.

 

I'm just wondering which side of the fan should face OUTWARDS?

 

 

[+Gary7 Subscriber²]

It is to face so that it exhausts hot air out of your PC, usually that will be with the logo on the inside of tha case. Most fans also have an arrow telling you the direction of air flow.

[Mindovermaster Global Moderator]

The sticker side, or the grill, is the output.

[Technique]

Well either i've now installed it incorrectly (i've just put the label with the red writing to the outside) or i've had it installed incorrectly for years because the wire that connects to the motherboard is now no longer long enough (without loosening the tie).

 

The arrow is pointing to the outside now anyway.

 

Oh 7 i also have a front fan.

[George P Global Moderator]

As far as I know, the rear fan is always pushing air out, specially if you have front fans which pull air inside.   Fans on the bottom should also pull air in while fans on the top, IMO, should push air out as well, because hot air goes up.

[Technique]

10 minutes ago, George P said:

As far as I know, the rear fan is always pushing air out, specially if you have front fans which pull air inside.   Fans on the bottom should also pull air in while fans on the top, IMO, should push air out as well, because hot air goes up.

Yeah that's what i was thinking also.

 

But i was at the time wondering which way around i should place the fan. Side 1 or side 2.

[+Gary7 Subscriber²]

3 hours ago, Technique said:

Yeah that's what i was thinking also.

 

But i was at the time wondering which way around i should place the fan. Side 1 or side 2.

Your question was answered many times. The side with the logo faces in to the case the side without the logo faces towards the rear. That side blow the air out of the case. If you want to test it hold a tissue on it, it will go with the air flow.

[xendrome]

There are typically arrows on the plastic that show the airflow direction, but yes, air should flow from front to back.

[Mindovermaster Global Moderator]

2 minutes ago, xendrome said:

There are typically arrows on the plastic that show the airflow direction, but yes, air should flow from front to back.

Not all, but yes most 

[+Gary7 Subscriber²]

I had no idea it took so may posts to determine the direction of air flow on a case fan.

[Mindovermaster Global Moderator]

11 minutes ago, Gary7 said:

I had no idea it took so may posts to determine the direction of air flow on a case fan.

I think he just missed the point with our other information...

[Rail Grinder]

The arrows are actually right there on the 3rd picture above your thumb.

 

The one pointing to the edge points to the direction of airflow, while the one pointing along the fan indicates rotation (not as important).

 

You would want to install the fan so that the arrow points to where you want the air to flow. Optimal direction for the rear is outwards as per everyone else's suggestion.

 

 

[Hum]

Without looking at others posts, I always thought Rear fans sucked out heat, while a Front fan blew in air.

[Rail Grinder]

20 minutes ago, Hum said:

Without looking at others posts, I always thought Rear fans sucked out heat, while a Front fan blew in air.

Yeah, that's the most logical and traditional airflow method.

[techbeck]

36 minutes ago, Hum said:

Without looking at others posts, I always thought Rear fans sucked out heat, while a Front fan blew in air.

Always made sense to me considering that the PSU blows out.  Anytime I built a PC (which has been a while) I always faced the rear fans out.  Side fans out as well as the top fans.

[DevTech]

My post from another thread:

 

There is rarely such as thing as "good air flow" - most people use the term mean some sort of imaginary diagram in their head of what the air is doing but in almost every case where is gets a real world test with a heat sensor gun, the imagination is wrong because humans and air think differently.

 

Without test equipment, the single thing completely in your power to accomplish is to aim a fan straight at the item you want to cool. With a modern mobo, it becomes trivial and most people use too many fans.

 

1. blow cool air from outside across cpu water radiator - in typical case, this means turning the fans around to blow the other way.

 

2. only in rare cases can you do anything about the typically weird GPU cooling, but when lucky give it cool air.

 

3. power supply comes with a fan - usually not much can be done with it

 

4. a case fan to blow cool outside air on mobo - usually any slow air movement is good enuff

 

5. a case fan to blow cool outside air on hard drives - usually any slow air movement is good enuff

 

6. rip out all other case fans - they typically just mess things up

 

-------------------------------------------------------------

 

It is so hard to get people to wrap there head around  a subject where "everybody knows" the answer. The old suck cool air in the front, blow out back myth was promoted by OEM manufacturers like Dell and HP during a time in computer history when components generated far less heat and the OEMS would also tweak the system with tight fitting cases and plastic air ducts all over the place.

 

So since I had a recent post handy, who knows, I might help somebody consider the mythology involved:

 

1. Sucking air requires suction! Suction requires a completely air tight enclosure.

 

2. Blowing air out of the case is similar to suction. A fan blowing outwards will grab the easiest available air which is usually nearby holes in the case. A fan blowing out is just generating Noise for almost no cooling effect.

 

3. Even if you had completely sealed suction which NEVER happens in real life, the air can still decide to do weird things which is why in the real engineering world air flow gets TESTED. Cars, airplanes, computer cases - all the same mysteries of Fluid Dynamics and Turbulence. So if you don't own a Heat Sensor Gun, it's all just guesswork.

 

4. What happens if you blow air inwards instead? A) it is cool air B) you know where it is going for about 6 inches C) it has no problem finding an exit route in a typical leaky case

 

[DevTech]

10 minutes ago, techbeck said:

Always made sense to me considering that the PSU blows out.  Anytime I built a PC (which has been a while) I always faced the rear fans out.  Side fans out as well as the top fans.

Wow - that's a lot of fans doing nothing. Rip out all the fans blowing air out and leave the nice big air holes in their place. Most likely your temp measurements will be the same or lower and your ears will feel a liitle bit better.

[DevTech]

28 minutes ago, Rail Grinder said:

Yeah, that's the most logical and traditional airflow method.

Traditional = Yes.

Logical = No. The fault in the logic is the word "suck" - there is simply zero "suck" in a typical computer case.

[+JHBrown Subscriber¹]

For optimal performance, exhaust on the rear/top of the case, and intake up front. Here is the best for gaming, more FPS(Uber GPU cooling)...

 

 

[Mindovermaster Global Moderator]

Dev, just drop it. The OP got the message, don't give him a history lesson...

[techbeck]

9 minutes ago, DevTech said:

Wow - that's a lot of fans doing nothing. Rip out all the fans blowing air out and leave the nice big air holes in their place. Most likely your temp measurements will be the same or lower and your ears will feel a liitle bit better.

Just one case I bought.  Back when I wanted one that had blue lights and everything.  Had two big fans on the front blowing air in....small fan on the back, top, and side across from the CPU fan.  Fans didnt cause a lot of noise actually.  And that was back when the IDE ribbon cables were a PITA the route so they did not block airflow.  So helped lower the temp a little.  Most cases I bought just had a couple in the front and then the back.

[techbeck]

8 minutes ago, JHBrown said:

For optimal performance, exhaust on the rear/top of the case, and intake up front. This is best for gaming, more FPS(Uber GPU cooling)...

 

 

Geesh....guy i used to work with actually suggested this.  Coworkers CPU fan died and his fix was to leave the case open and place a desktop fan to blow air on the CPU to keep it cool.  Needless to say, he was not around much after.

[Hum]

8 minutes ago, JHBrown said:

 

I've done just that when the weather was hot and I had a case heating problem.

 

I simply set a floor fan aimed in the case and let it blow in.

[DevTech]

9 minutes ago, Mindovermaster said:

Dev, just drop it. The OP got the message, don't give him a history lesson...

Oh but that is too narrow a point of view.

 

If I thought that the only recipient of what I type in any thread was the OP then I wouldn't be bothering with any of this. I am trying to help people for the benefit of all mankind so to speak since this information is available to the mighty Google.

 

Of course in this particular case I have almost no chance of stemming the tide of miss-information in the old and tired "blow air in the front and suck it out the back at the top because heat rises blah de blah useless meme"

 

Science is not about logical thinking which in this case seems to totally fail people, but instead the root of all Science is TESTING. You can use logic to form a starting hypothesis, but in the end the TESTING is the Science.

 

 

 

[DevTech]

17 minutes ago, JHBrown said:

For optimal performance, exhaust on the rear/top of the case, and intake up front. Here is the best for gaming, more FPS(Uber GPU cooling)...

 

 

If you read my posts here, your part A) does nothing

 

But your part B) blow air right on the thing that needs cooling is exactly right and the picture is a great example of something that would actually work. If the fan has good bearings and runs at a slow speed, it will cool better and quieter than most solutions!

 

Now spray the whole thing in lime green paint and slap a NVIDIA logo on it...