Top intake or exhaust?

zachary80 · Post by **zachary80** » Tue Jul 06, 2004 11:17 am

On my non-silent OC machine, I just now noticed (after a year

) that my top fan on my case is an intake instead of an exhaust.

This computer is for overclocking, so heat is the most important thing, not noise. The front has two 80mm intakes the top is 80mm (intake right now), then there is a 80mm exhaust on the back.

Which should it be?

Post by **Ralf Hutter** » Tue Jul 06, 2004 12:34 pm

Exhaust, so it works in conjunction with the natural flow of air in your case, which is "hot air raises".

Mr.Radar · Post by **Mr.Radar** » Tue Jul 06, 2004 2:00 pm

Generally you want air to go from the bottom front of your case to the top rear. If you want a good forum for OC'ing advice check out www.ocforums.com

zachary80 · Post by **zachary80** » Tue Jul 06, 2004 2:23 pm

For silent computers:
I thought have the front intake on the case made it louder, and that you were supposed to seal it off? Or is a fan just not needed?

Post by **Rusty075** » Tue Jul 06, 2004 2:46 pm

Try it and find out!

The beautiful thing about "which way should my fan blow?" questions is that you can answer them yourself, for free!

In the 3 hours since you posted your first question, to the time that I wrote this response you could have tested every possible fan configuration and found out exactly which one gave you the best combination of temps and noise....

Now having said that....

As a general rule, intake fans are nearly useless, whether you're overclocking or going silent. The intake area is needed, don't seal it off, but the fan there is doing nothing but making noise. Unplugging those fans will likely do almost nothing to your temps, but will make a real impact on the noise of your machine.

About the only thing intakes are good for is cooling components that are directly behind them, like HDD's.

(I say "general rule" because there are situations where intakes are useful, and even prefered, but they are very much the minority of situations)

acaurora · Post by **acaurora** » Tue Jul 06, 2004 3:17 pm

Like everyone is saying, flip the exhaust so it pulls air out. Otherwise you're bringing warm air into your already warm case. So have the exhaust in the back blow out, as well as the top. Having fans in the front pulling air in is optional, as the fans blowing out will naturally create a vacuum, thus pulling in air without having to add additional fans. I only have a fan in the front because my stupid Maxtor drive runs rather hot, even though it isn't a 10K RPM like a raptor ~.~

sthayashi · Post by **sthayashi** » Tue Jul 06, 2004 5:07 pm

Question: Wouldn't it be better to have the top fan be an intake so that fresh or fresher air could get to the PSU? Or would that only be applicable with a duct?

acaurora · Post by **acaurora** » Tue Jul 06, 2004 5:10 pm

sthayashi wrote:Question: Wouldn't it be better to have the top fan be an intake so that fresh or fresher air could get to the PSU? Or would that only be applicable with a duct?

top as exhaust > top as intake. As stated before, top as intake only pushes the hot air back into the case. The objective is to get hot air OUT of the case, and a top fan would be the most effective way.

sppenguin · Post by **sppenguin** » Tue Jul 06, 2004 5:53 pm

just remember some basic science

Heat rises
Pressure tries to reach equilibrium

It is more imparitve to have warm air being pushed outa your case, than for possibly cool, most likely not, air being pushed in. Not only for temperature reasons, but to have an intake there would go against the natural flow of your case, probally causing more harm than good.

One question i have for the rest of you :

SIde panel - Intake or Exhaust
I've used it as an exhaust and intake, and in general, i think i like intake better. I'm not really sure how it relates to the two principles i stated above.

acaurora · Post by **acaurora** » Tue Jul 06, 2004 6:03 pm

Intake introduces another opportunity for dust. However, if your intake is in the right location, and the circumstances are right, it can be beneficial, say, if it's positioned right above your video card. However if it is, say, pointed at your RAM, wouldn't help much. My last case had a side mount, but I just sealed it off, and it worked fine

zachary80 · Post by **zachary80** » Tue Jul 06, 2004 10:04 pm

Heh, I didn't need an explaination for everything. I know warm air rises, but the whole reason I posted was because my machine was built with an intake, and I thought this was wrong. Posting here confirmed my thoughts.

Also, for a different computer (the quiet one), is it bad to seal off the front? I thought I heard that I should but that doesn't make much sense...

acaurora · Post by **acaurora** » Wed Jul 07, 2004 12:43 am

You shouldn't. If you do, no air gets in, and that's bad ~.~

the_smell · Post by **the_smell** » Wed Jul 07, 2004 3:55 am

I agree with zachary80, sealing off the front probably wouldn't be a good idea. But if you do get tempted to make you computer less noisey, ducting from the top to the back of the psu will help (you'll probably be able to do it with just a good bit of plastic). How this will affect you temperatures depends on how good your airflow is elsewhere (a nice 120mm exhaust fan is good) - sorry stating the obvious there.
Experiment, you may find something new out!

orionlion82 · Post by **orionlion82** » Mon Jul 12, 2004 11:47 pm

hmmm, if it werent 4 am i would pull my intakes off, and set the others to exhaust... can i use the two extras as "stirrers" to circulate air throughout the inside of the case, i was having mixed results with a 90 mm spare, but is it a practice that is worthwhile or a no-no? thanks folks,.