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Side fan blows air into case

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May 2, 2008 2:29:58 AM

I have a NZXT Apollo case. On the side window, there is a 120mm fan blowing air INTO the case. On the back, there is a 120mm fan blowing air OUT of the case. Was my side fan put on reversed? Should it be blowing air out instead?
May 2, 2008 2:47:34 AM

no, everything is as it should be.

May 2, 2008 3:03:53 AM

I have that case, pretty nice. I put a 3rd 120mm in the front, keeps things frosty cold ;) 

Only real prob I have is the way the bottom HD cage is positioned, Ive almost snapped my SATA connectors off a couple of times, guess I need to find some 90 degree angled cables.
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May 2, 2008 3:33:30 AM

Quote:
The idea is for that side fan to blow cool air from outside the case straight onto the graphics card and mainboard. Leave it installed as it is...


Problem with that is it's gonna be blowing the hot air from the graphics card all over his other components. I've personally took the side of my case and setup a large room fan to blow cool air onto my mobo etc. My CPU temps actually increased 1-2 degrees.

OP, check all your temps, then try flipping the fan the other way and check temps again.

As long as there's a way for air to come in through the front of the case having the side fan acting as an exhaust should lower your temps.
May 2, 2008 3:38:34 AM

Why is it everyone thinks fans should always blow out and think the opposite of what everything should be?

Rear - Out
Side - In
Front - In
PSU - Out
May 2, 2008 5:08:06 AM

apache_lives said:
Why is it everyone thinks fans should always blow out and think the opposite of what everything should be?

Rear - Out
Side - In
Front - In
PSU - Out


I'm basing this off of experience, i'm pretty sure my temps didn't lie to me. Regardless i will try it again to be sure it wasn't a fluke.

Also airflow acts much like a liquid, minus the mass, so sucking cool air onto a hot component is good. However that cool air will get hot passing over/through said hot component and that hot air will continue to flow across the rest of the components. This will cause all but the first component to either remain the same temp or increase.

Having it blowing out will cause suction to happen at the front of the case, preferably assisted by a front intake fan, and draw cool air in from the front. The side exhaust will draw cool air across the graphics card and out the side of the case. The rear exhaust will draw cool air, with the assistance of the front intake fan, across the motherboard, across the cpu, and out the rear.

Additionally you don't want to have more intake then exhaust, this will cause stale air to build up in the case likely near the exhaust fan. Which for the OP is near the cpu. Ideally you want to have the same or close to the same intake as exhaust, to promote smooth airflow throughout the case.
May 2, 2008 5:27:19 AM

Ok i just double checked my theory.

My CPU temps before the test was 46,46,37,39. This was with my case open and the house fan off.

I then turned the house fan on low. It is facing directly into my case from about 3-4ft away. And my temps changed to 48,48,39,42 after about 2min.

I then turned the fan off, case still open, and the temps it gave me after 2 min were 46,46,38,39.

I dunno, but i think the temps speak for itself.
May 2, 2008 5:42:34 AM

Topic:
Quote:
Side fan blows air into case

That's the correct way.

Too many fans disrupt the proper airflow and do not aid in cooling.
Use a metal nibbler tool ($12-20 @ any hardware store) and remove the exit fan grill on the case for an average 80% better airflow.
May 2, 2008 6:00:42 AM

lucuis said:
Ok i just double checked my theory.

My CPU temps before the test was 46,46,37,39. This was with my case open and the house fan off.

I then turned the house fan on low. It is facing directly into my case from about 3-4ft away. And my temps changed to 48,48,39,42 after about 2min.

I then turned the fan off, case still open, and the temps it gave me after 2 min were 46,46,38,39.

I dunno, but i think the temps speak for itself.


Like ZOldDude has just said, too many fans disrupt the proper airflow. By using the case fan, you overpower the other fans that you may have in your case, causing the air to not flow, but rather go all over the place. And that's not as efficient. If you have a small side fan, it doesn't disrupt the flow, it merely adds to the cool air in the flow. I suppose it may disrupt the flow a little, but the benefit outways that.
May 2, 2008 6:14:15 AM

That's exactly what i thought, however i didn't take into account the smaller 120mm fan not disrupting the airflow as much. So in that sense my test is flawed.

My plan is to have 3 intake fans up front, i all ready have 2 exhaust fans, but without a third the intake would be too much. So in my case i think i'd benefit most have the side fan acting as an exhaust.

Of course i'll never know till i try it.
May 2, 2008 6:25:26 AM

yeah, I think it is a good idea to try it. It might help. And it is better to have more exhaust than intake.
May 2, 2008 7:23:21 AM

Having negative pressure (more exhaust than intake) is better because the exhaust fans will also act as intake fans with the various vents on the case, which decreases hot air pockets and keeps stuff cooler :) 
a b ) Power supply
May 2, 2008 7:24:59 AM

lucuis said:
My plan is to have 3 intake fans up front, i all ready have 2 exhaust fans, but without a third the intake would be too much. So in my case i think i'd benefit most have the side fan acting as an exhaust.


Don't forget the PSU!
May 2, 2008 10:36:30 AM

mi1ez said:
Don't forget the PSU!


What do you mean?
May 2, 2008 11:50:30 AM

Lucius, does your experiment take into account all the pressure etc inside the case as your case was open, removing the need for any exaust at all?
a b ) Power supply
May 2, 2008 12:00:56 PM

lucuis said:
What do you mean?


I mean don't forget that the PSU also exhausts air from inside the case.
May 2, 2008 12:08:36 PM

The little side fans on some cases seem kind of worthless to me.
On my Raidmax case, the side fan sits directly in front of and inline with a large exhaust fan on the back of the case. Any air that little fan blows in is instantly drawn right out the back of the case. Maybe it would be better turned around and used as an exhuast? I'll have to experiment a little. But as is everything runs cool, so I don't worry about too much.
May 2, 2008 12:30:41 PM

I have a raidmax scorpio case and have 4 intake and 4 exhasut fans not counting the PSU or other device fans. Never had any heat issues.
May 2, 2008 8:37:20 PM

I have 5 140mm fans and 2 120mm fans on my case alone, not to mention the 120mm on my TRUE heatsink.....

I went with a volt mod to slow down the fans so the case is darn near quiet, but still moves alot of fresh air.....

Location of fans are.... 2 x140mm on top blowing out, 1x140mm on side blowing in, 1x140mm and 1x120mm in front blowing in, 1x140mm on bottom of case blowing in and 1x120mm fan blowing out in the back...

On the CM690 case, the psu is situated so that is circulates its own fresh air...

Oh, forgot my point..... Air flow is important, a wrong placed fan can disrupt the whole case causing a dead spot where hot air accumulates ...... So I went with high CFM but quietly....
May 2, 2008 11:32:46 PM

mi1ez said:
I mean don't forget that the PSU also exhausts air from inside the case.



Ah yeah, my PSU fan is situated at the top of the PSU. So it's blowing straight up. It's a good thing the rest of my case is sealed of pretty good, so hopefully very little hot air from it is getting in there.



And one of the so called intake fans i'm putting in is actually a intake.exhaust. I'm putting it in front of the PSU.
May 3, 2008 2:14:31 AM

Heres some airflow info for ya. My side intake fan had a metal grill over it, slowed airflow to a crawl, but made it alot quieter. After I took that grill off, I saw a 2-3 degree drop in both CPU and ambient temps. Plus my 8800GT barely goes over 50C.
May 3, 2008 3:45:36 AM

I maybe the only person to say either will work, just try it both ways to see what the results are.

Not all cases act the same.

On my case I have the side fan blowing air out. My case also has a fake 140mm fan in the front, so the only thing that is turning it is airflow.

When I had my side fan blowing in (I use fan controller), I turned my front 140mm fan all the way down, and the rear exhaust fan all the way down. Now the front fake fan stopped turning. Then I turned up the rear exhause a lil bit to where the front fake fan started turning well. Then I turned the side fan on full. Guess what, the front fake fan stopped. It was basically the indication that my side fan, from where its placed hinders airflow.

Now I've down that on my other cases, but not everything will be as it seems, since I've seen temps increased on different cases.

So that's why I say try both, and stick what works best.
May 3, 2008 12:29:21 PM

First post alert! Hello all.

I have an X-Cruiser case. I have this arrangement right now.

Front - 2 x 80mm - In
Top - 1 x 80mm - Out
Rear - 1 x 120mm - Out
Side - Took the original 80 from the rear and removed the tube - Out
I have used a PCI slot fan for my 7900GT, I've hated this card from day one.

My temps dropped more than they were. I debated over having it blow in or blow out.

I already have an E8400 and PC&C 710W in the boxes. After our imminent bathroom remodel, I'll be getting the Motherboard, VC and Memory. I'll be cutting the holes out with my Dremel.

According to Speedfan my case is at 23C, which I believe is around 73 Fahrenheit.
February 27, 2009 5:17:52 PM

It's a case by case situation (no pun intended) although any case i've ever tested has always been side fan blowing out = cooler. More exhaust is best.

The biggest difference over time was the dust build up was dramatically reduced blowing out. Think about it, why blow dust straight onto your cpu or gpu?
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