Which position is better for fans? In or Out?

[AtomicDude512]

I have three case fans in a Chieftec tower case. Which configuration would be better?

a) 2 output, 1 intake
b) 1 output, 2 intake

Output being in the back, Intake in the front.

Any suggestions? Thanks!

 

[jmorrell]

2 output, 1 intake is the preferred fan setup. This gives your case negative air pressure, which is better at removing heat from the case.

 

[AtomicDude512]

Thanks!

 

[svidanag]

Have he ones in the front intake and the ones in the back ouput.

 

[godmare]

Originally posted by: jmorrell
2 output, 1 intake is the preferred fan setup. This gives your case negative air pressure, which is better at removing heat from the case.

I disagree.
Better to have about equal or slightly positive pressure, with filters on the intake fans to limit dust. With negative pressure, the air must be equalized- often times by sucking air in from wherever is convenient, such as cd and floppy drives. This gunks up your drives, and invites the enemy of case cooling onto your heatsink, motherboard, etc.: DUST.

 

[Pancho7]

ditto godmare's post.
There should be an even airflow going into and out of the case.
Of course there should be the least amount of obstruction in case, otherwise none of it will matter that much.

 

[deerslayer]

Originally posted by: godmare

Originally posted by: jmorrell
2 output, 1 intake is the preferred fan setup. This gives your case negative air pressure, which is better at removing heat from the case.

I disagree.
Better to have about equal or slightly positive pressure, with filters on the intake fans to limit dust. With negative pressure, the air must be equalized- often times by sucking air in from wherever is convenient, such as cd and floppy drives. This gunks up your drives, and invites the enemy of case cooling onto your heatsink, motherboard, etc.: DUST.

Agreed.

 

[SWScorch]

I'll chime in here to add yet another dissenting opinion. It is true that in a perfect system, the airflow enetering the case would equal the airflow leaving the case, and all would be hunky dory. But that never happens in the real world. I have also considered it better to have negative pressure, as it draws the heat out, as noted above. Yes, it is true that this usually means more dust, and your drives and vents get gunked up, but it generally means slightly better cooling.

So, really, its up to you. You must weigh the pros and cons of each and decide for yourself which is better.

Negative:

Pros - slightly increased cooling due to faster removal of heated air
Cons - more dust and gunked up vents

Positive:

Pros - less dust
Cons - slightly decreased cooling.

 

[Jhhnn]

If that's a sx-antec clone, forget filters, they're an impractical PITA on that box, without mods. Put two fans in the rear, exhausting, forget the front fan, it won't do diddley.

Those boxes flow air so well that you may be able to series wire the two rear fans to reduce noise without raising temps perceptibly...

 

[Metalloid]

Originally posted by: LyNx01

Originally posted by: godmare

Originally posted by: jmorrell
2 output, 1 intake is the preferred fan setup. This gives your case negative air pressure, which is better at removing heat from the case.

I disagree.
Better to have about equal or slightly positive pressure, with filters on the intake fans to limit dust. With negative pressure, the air must be equalized- often times by sucking air in from wherever is convenient, such as cd and floppy drives. This gunks up your drives, and invites the enemy of case cooling onto your heatsink, motherboard, etc.: DUST.

Agreed.

This is also my preference. And I don't think that having negative air pressure is actually proven to give better cooling, but having positive air pressure is proven to get rid of dust (of course you need fan filters, otherwise the whole thing is pointless).

 

[Baileybbk]

If I remember my thermodynamics correctly (encumbered fluid flow etc) negative pressure in the case should cool the components better (of course with a build-up of dust). Then again, there are so many factors involved (components, case design, etc), only testing would determine for each setup which would work better!

When I've had to put high performance computers in dusty environments - we put the negative pressure computers in a positively pressured enclosure....not a home setup, but very effective at both cooling and keeping it dust free.

None of this really helps the decision aye.........

 

[Jhhnn]

All this stuff about negative vs positive pressure is a total misdirection play. Computer fans generate such small pressure differentials that it's extremely difficult to actually measure them, and the air density differences are insignificant, having no effect on heat transfer. It's all about flow, and moving the warmest air out of the case to allow the heat to dissipate outside the box. well placed exhaust fans do just that, pushing the warmest air near the processor and vidcard out the back, while makeup air enters wherever it can. Front fans push cool air in, but don't insure that the warmest air is leaving, or where the air is exiting. With restrictive cases, adding front fans can help, only in the sense that they reduce the pressure differential the rear fan must work against. That's not a problem with any of the Antec clones.

Apply a little scientific method, you'll see what I mean.

 

[cavemanmoron]

you can always leave one side cover off too!
thats what i do on most of mine here,

 

[Pancho7]

Adding a filter on my chieftec/chenming case was a breeze(hehe).
Found some porous filter material originally intended to be a pre-filter to a shopvac. It's thickness(3/8") makes it perfect to be placed behind the front plastic bezel/cover, in front of the aluminum case fans.
I didn't even have to remove the plastic cover, I just slid the material straight up from the opening at the bottom.
It does a great job too. To clean it we just use our trusty filter queen vacuum applied to the front of the plastic grille, no more dust.

 

[Metalloid]

Originally posted by: cavemanmoron
you can always leave one side cover off too!
thats what i do on most of mine here,

I have actually found that a 120mm intake on the side and a 120mm exhaust on the top is more effecient then just leaving your case open.

 

[AtomicDude512]

Originally posted by: Metalloid15

Originally posted by: cavemanmoron
you can always leave one side cover off too!
thats what i do on most of mine here,

I have actually found that a 120mm intake on the side and a 120mm exhaust on the top is more effecient then just leaving your case open.

Of course it is! Because it has a airflow "pathway", whereas the case side off the air dosent really have a path to follow.