Intake or Exhaust?

[DarthShoppingMaul]

Hi I'm building a gaming computer soon and I'm wondering which fans should be intake and which should be exhaust? Thanks.

Here's my part list: http://pcpartpicker.com/p/wmqmdC

 

[CBender]

As a rule of thumb : one fan as front intake and one fan as rear exhaust. After that I always prefer to have better exhaust than intake. For example : one fan intake, one rear exhaust, one top exhaust. And from there you add fans.

 

[DustinV]

The above answer is the worse fan configuration. You want either the same amount of intake and exhaust fans or more intake than exhaust fans.

More exhausts causes a vacuum (lack of air) inside your pc

 

[Rogue Leader]

As a rule of thumb : one fan as front intake and one fan as rear exhaust. After that I always prefer to have better exhaust than intake. For example : one fan intake, one rear exhaust, one top exhaust. And from there you add fans.

Depends on location though. Positive pressure (more intake fans, or intake fans are larger than exhaust) helps keep dust out and if you have a system hat doesn't push the overclock this is beneficial.

Your rule of thumb is a good starting point, but if its in a dusty place or a carpeted room, positive pressure is a good idea.

 

[superninja12]

As a rule of thumb : one fan as front intake and one fan as rear exhaust. After that I always prefer to have better exhaust than intake. For example : one fan intake, one rear exhaust, one top exhaust. And from there you add fans.

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You want more air into your case than out the thumb rule should be 2 fans air in 1 fan air out.
this is called positive air pressure, bender just described negative air pressure.

anyways fans are PWM fans.

 

[Rogue Leader]

The above answer is the worse fan configuration. You want either the same amount of intake and exhaust fans or more intake than exhaust fans.

More exhausts causes a vacuum (lack of air) inside your pc

Incorrect, more exhaust is actually better for cooling purposes as it pulls the hot air away quicker. However the disadvantage is that it causes dust buildup inside the case. More intake fans cause positive pressure which helps keep dust out, but doesn't cool as efficiently.

You need to pick depending on location of the computer, how dusty the room is, etc.

 

[CBender]

The above answer is the worse fan configuration. You want either the same amount of intake and exhaust fans or more intake than exhaust fans.

More exhausts causes a vacuum (lack of air) inside your pc

Vacuum? Really?

 

[geofelt]

Obviously, opinions vary.
The nice thing is, that you can experiment; it is not hard to reconfigure fans.

My preference is for a positive airflow where all the intake air comes in through filtered front intakes.
That keeps your case cleaner.
Let the hot air exit where it will.
In this case, two 120mm intakes and perhaps just one exhaust fan for airflow directional control.
If you make the exhausts too powerful, it will draw in unfiltered air from other openings.

IN this build, I think a liquid cooler complicates things from two points of view.
1. A liquid cooler is not necessary, a 14nm skylake processor, even overclocked will be perfectly happy with a mid range air cooler.
The limit to overclocking skylake is not temperature but the vcore you can tolerate.
Only past 1.40v does the chip get toasty.
And, I would go no higher than that.
A noctua NH-U14s would be cheaper and perform better.

2. How you orient the radiator is an issue. If you orient to draw in cold air from the outside, you will cool the cpu better, but you have little hope of a clean pc.
And the hot air will increase the temperatures of the motherboard and the graphics card.

OTOH, if you set it to exhaust, your cpu will not be cooled as well. Actually, I prefer this orientation.
I would use the radiator as exhaust and omit the rear exhaust fan.

With a tower air cooler, there is no issue; all the hot cpu air is going directly out the back of the case.

 

[Bearmann]

The above answer is the worse fan configuration. You want either the same amount of intake and exhaust fans or more intake than exhaust fans.

More exhausts causes a vacuum (lack of air) inside your pc

Incorrect, more exhaust is actually better for cooling purposes as it pulls the hot air away quicker. However the disadvantage is that it causes dust buildup inside the case. More intake fans cause positive pressure which helps keep dust out, but doesn't cool as efficiently.

You need to pick depending on location of the computer, how dusty the room is, etc.

^ This.

 

[Onus]

My own overclocks are not high enough to stress my cooling arrangements where any measurements would likely be meaningful. What I have read, however, is consistent with Rogue Leader's comments. In any case, you want to create a definite flow through the case. You should also keep in mind that the PSU fan is an exhaust. Unless it draws its own air from beneath the case, too many other exhaust fans will make the PSU fan have to fight a lot harder to cool the PSU. As a side note, it would not surprise me if this is a contributing factor in early Corsair "CX" PSU failures. I tend to use a front intake, a rear exhaust, the PSU gets its own air, and sometimes a top exhaust; all fans are low speed, and plenty of dust and cat hair accumulates on the front filter.

 

[DarthShoppingMaul]

The above answer is the worse fan configuration. You want either the same amount of intake and exhaust fans or more intake than exhaust fans.

More exhausts causes a vacuum (lack of air) inside your pc

So which ones should be intake and exhaust? I have a watercolor on top so should those be intake or exhaust? i also have 2 fans in the front and one in the rear? Which should be intake and which should be exhaust?

 

[DarthShoppingMaul]

The above answer is the worse fan configuration. You want either the same amount of intake and exhaust fans or more intake than exhaust fans.

More exhausts causes a vacuum (lack of air) inside your pc

Incorrect, more exhaust is actually better for cooling purposes as it pulls the hot air away quicker. However the disadvantage is that it causes dust buildup inside the case. More intake fans cause positive pressure which helps keep dust out, but doesn't cool as efficiently.

You need to pick depending on location of the computer, how dusty the room is, etc.

its my bedroom so there is almost no dust cause we clean it daily
how about the front two are intake, and the watercolor on top and the rear fan are both exhaust?

 

[DarthShoppingMaul]

My own overclocks are not high enough to stress my cooling arrangements where any measurements would likely be meaningful. What I have read, however, is consistent with Rogue Leader's comments. In any case, you want to create a definite flow through the case. You should also keep in mind that the PSU fan is an exhaust. Unless it draws its own air from beneath the case, too many other exhaust fans will make the PSU fan have to fight a lot harder to cool the PSU. As a side note, it would not surprise me if this is a contributing factor in early Corsair "CX" PSU failures. I tend to use a front intake, a rear exhaust, the PSU gets its own air, and sometimes a top exhaust; all fans are low speed, and plenty of dust and cat hair accumulates on the front filter.

ok so front intake, rear exhaust, and the top is my watercolor so should the watercolor fans be exhaust or intake?

 

[Rogue Leader]

The above answer is the worse fan configuration. You want either the same amount of intake and exhaust fans or more intake than exhaust fans.

More exhausts causes a vacuum (lack of air) inside your pc

Incorrect, more exhaust is actually better for cooling purposes as it pulls the hot air away quicker. However the disadvantage is that it causes dust buildup inside the case. More intake fans cause positive pressure which helps keep dust out, but doesn't cool as efficiently.

You need to pick depending on location of the computer, how dusty the room is, etc.

its my bedroom so there is almost no dust cause we clean it daily
how about the front two are intake, and the watercolor on top and the rear fan are both exhaust?

That would be a good way to go, should work perfect

 

[Darkbreeze]

The only time I'd be worried at ALL about having positive pressure, is if you're in a room where dust or dirt are prevalent, and you have an older case without filtration. If it's a fairly dust free environment (Yes, there are NO fully dust free environments in the average home, but there are certainly varying levels) or you have filtration on your case, you absolutely want a negative pressure system if cooling performance is more important than dust suppression. Even with a positive pressure system, there will still be dust, just not as much.

A cheap air compressor or a few cans of compressed air, to be used every month or two, makes this a moot point anyhow.

Negative pressure systems can result in as much as a 15°C internal case air temperature difference, depending on the number of fans and the fan profile. I always lobby for either an equal or negative pressure system, usually equal, in order to accomodate the best of both worlds, but if there are thermal issues or absolute performance is required, then negative pressure vastly outperforms positive pressure in every scenario.

 

[CBender]

The AIO depending the location: TOP = exhaust
FRONT = intake

If you install fans as intake on top: you would against the natural direction of the air, hot goes up cold goes down. And you would insert hot air into the case dissipated from the radiator.

 

[Darkbreeze]

I'm usually for the top mounted radiators being in an exhaust configuration, as those locations would normally be, but there are exceptions. If you can get enough airflow through the case to ensure you're not using unacceptably warm air for radiator cooling, then it's fine. If not, as when only a single front 120mm intake is being used, you might want to carefully consider the options.

In this case, with the Enthoo Pro M, if you put two 140mm fans in front and don't hamstring them with a silent profile then it's probably fine for the top mounted radiator to be in an exhaust configuration. Honestly it almost has to be anyhow. Four intake fans (Front and radiator at the top) with only a single rear exhaust isn't going to be very efficient or have very good performance in any event.