Should my computer fans suck air in or blow it out? - Diagram attached


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I have the SilverStone HTPC chassis below, it came with three 120mm fans included, one of the fans is placed on the left side next to the hard drive and two fans are placed on the right side side next to the CPU and DVD drive (I don't have a graphics card).

 

Right now, the fan next to the hard drive is sucking air in, and the two fans on the right side next to CPU blow air out. I now see on the SilverStone website a diagram with all three fans sucking air in. I am confused about this because I always understood that one of the fans should at least blow air out so that there can be some airflow, if all of the present fans only suck the hot air in, it will be more difficult for the hot air to make its way out.

 

I would value some input to work out how to best place the three fans, if blowing or sucking air.

 

The picture below is the SilverStone fan set up and diagram, there are no fans at the rear!, I don't have the zoomed in CPU cooler on the diagram. Full chassis specs and more photos  at http://www.silverstonetek.com/product.php?pid=233&area=en

 

GD04-NT01-E.jpg

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You can buy fans and add them to your rear case...  it's easy installation.

 

That will help air flow smoothly.

 

Front or back ... suck air in..

 

top of case: blow air out where the heat goes up.

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I should add that I have a cheap motherboard with no spare connections for more fans, and even if I was able to, if possible I would like to fix it with what I have now, I have the feeling that three fans is enough for this type of case and APU AMD A10 with no graphics card, it just needs optimization. 

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I should add that I have a cheap motherboard with no spare connections for more fans, and even if I was able to, I would like to keep things as simple as possible with what I have.

 

get the split connections ... ask the computer store and ask for them..    

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Blow air out... it will suck out the hot air.

 

Never, or rarely have air blow in. That air could be hot and just increase the temp.

 

But if you have one in the front blowing out and one in the back blowing in that would be best.

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I'm fairly certain fan configuration doesn't make a huge difference in temps as long as its balanced (not all fans blowing in or out) other than maybe blow air out of the top of the case since heat rises.

 

One thing to consider is dust, if your fans have filters on them you will want to maintain positive air pressure in your case (more air blowing in than out) that way the only dust going into your case gets trapped on the filters, making it easy to clean the filters and leaving the rest of the case relatively dust-free.

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My 8 fans blow air into my system, from the front and side, then I have 2 on the back plate blowing air out on my old system, and the case rarely got warm, an added bonus was the chassis temp sensors that were built into the front of it telling me what the cpu and gpu temps were, fan speed etc...

 

 

My new Coolermaster Silencio, rig has 2 blowing air into the case from the front, and one extracting from the rear (not counting the various fans on my gpus and cpu, the chassis fans came with the coolermaster case)

 

So although I cannot say what's best, as what's best for one isn't necessarily best for another, I would set up front and/or side fans to blow air into the rig, and any rear, to blow outwards (extract) if it were my pc :)

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get the split connections ... ask the computer store and ask for them..    

 

Great answers so far thank you. I only want to clarify that I am fairly certain that I don't want to buy anything else, regardless of price, $0.1 or $2, it doesn't matter, I will not buy it.

 

I feel that I have all I need for this to work once I learn how to best set it up.

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I always suck air OUT as low pressure will cause air to fill the case again which will warm up.

 

So basically the cycle goes, the air in your case gets warm and the fans suck it out which causes cold(er) outside air to fill the space (lower pressure inside the case) which gets heated and then gets sucked out again and it continues.

 

Sucking in cold air increases the pressure inside the case which causes the air the want to leave which would therefore take the warm air away but doesn't work as efficiently as the other way as they fight (in vs out air) so you get less cooling.

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Never, or rarely have air blow in. That air could be hot and just increase the temp.

 

Wow, nonsense.  airFLOW is what's needed so you flow air in from the front, out the back/top over the hot areas and outward.

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Shozilla has asked me by PM to mark his answer as best answer. He has been helpful but it seems more fair to keep the thread open a few days so that everybody can have a chance to be the best answer too.

 

So please don't PM me asking to mark you as best answer for a thread opened 20 minutes ago, let's wait a few days, thank you.

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Blow air out... it will suck out the hot air.

 

Never, or rarely have air blow in. That air could be hot and just increase the temp.

 

But if you have one in the front blowing out and one in the back blowing in that would be best.

Bad advice...In a typical case setup, (cool) air should flow in from the front/sides, and (hot) air exhausts out back/top fans. 

 

OP, if you don't have fan connectors on your motherboard, hook up the fans directly to the PSU. The only downside is they'll run 100% speed when your computer is on, which shouldn't be a big deal. Since it's a HTPC case, get fans that are quieter (might be slightly more expensive).

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I'm fairly certain fan configuration doesn't make a huge difference in temps as long as its balanced (not all fans blowing in or out) other than maybe blow air out of the top of the case since heat rises.

 

One thing to consider is dust, if your fans have filters on them you will want to maintain positive air pressure in your case (more air blowing in than out) that way the only dust going into your case gets trapped on the filters, making it easy to clean the filters and leaving the rest of the case relatively dust-free.

Actually, well placed fans and a some thought is more efficient than just placing a bunch of fans.

I re-did a gaming system for a local doctor - he had some clown build this thing, and he must have had 12-14 fans in it -- it was annoying loud.  He thought that was just how powerful gaming systems were - I showed him how much better it would be done correctly.  I threw away 8 fans, and it was reporting cooler temps than before when it sounded like a 747 @ take off.

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suck in when in the front, blow out when in the rear. You want air flow over the components with heat sinks. What is the best way in your case that you can have cold air flow and keep air moving in there?

Servers will have air that sucks from the front and blow out the rear...why do you think they are designed that way? It keeps air moving through the case.

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First up, what are you current temperatures reading? If they are low enough, then it's all good, nothing to worry about.

 

The way you have the fans set up now, means cool air will be drawn in from the sides, over your components, and forced out the back.

 

Is your power supply intake fan on the inside of the case, or facing outwards? If it is on the inside, then it will be drawing hot air out of the case, which may not be helping keep the PSU as cool as it could be.

 

If you would like to help that along by drawing air out of the back a bit faster, then invest in some decent silent fans. Good quality ones will come with various connectors, including a splitter.

 

As has been mentioned, you want to have a good flow of air passing through, with no negative, or positive pressure inside the case.

 

For an HTPC, I can recommend the Noctua NF-R8 and NFB9, depending on what size you need.

 

They both come with extension cables, splitters, and a low noise adapter cable, that reduces the speed, they also use noise dampening rubber fittings instead of screws.

I'd don't really like the colour of them at all, but then they are not for show, so... :)

 

 

 

EDIT: This is an interesting read... http://www.overclock.net/t/1219634/positive-air-pressure-what-you-need-to-know-to-keep-your-pc-clean-and-happy

 

 

 

 

 

 

 

 

I intend to take that best answer award away from shozilla. lol
Asking for best answer!? fo shame!!

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Follow the diagram they show, hook fans up to the molex connectors on the CPU and make sure they're quiet fans or get a fan controller to put in one of the bays. 

 

the diagram also correctly shows 3 in and 2 out. you should always have more pressure blowing into the case than out. in this case that is solved by 5 equal fans where there's on more blowing in, but it's all about the volume of air moved not the amount of fans. the reason for this is to create an overpressure in the case, this prevents dust from being sucked in.  Whereas if you followed another advice here and had only fans blowing out, you would have a HUGE under pressure in the case, and you would suck in all the dust in near the case. 

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you should always have more pressure blowing into the case than out. in this case that is solved by 5 equal fans where there's on more blowing in, but it's all about the volume of air moved not the amount of fans. the reason for this is to create an overpressure in the case, this prevents dust from being sucked in.  Whereas if you followed another advice here and had only fans blowing out, you would have a HUGE under pressure in the case, and you would suck in all the dust in near the case. 

 

Unless I am incorrect, that is not true. I have 3 cases that have 1 intake in the front, and 2 out the back and top. Unless they are pressurized different?

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Unless I am incorrect, that is not true. I have 3 cases that have 1 intake in the front, and 2 out the back and top. Unless they are pressurized different?

Positive pressure (more pressure blowing in than out) is best if you put filters on your intake fans, that way you keep dust in your case to a minimum. Otherwise you have dust being pulled into your case through all the gaps in the case, which gets the dust in hard to reach areas and fills the case with dust, as opposed to positive pressure with filters on the fans where you get little to no dust buildup in the case, only on the filters.

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You can buy fans and add them to your rear case...  it's easy installation.

 

That will help air flow smoothly.

 

Front or back ... suck air in..

 

top of case: blow air out where the heat goes up.

Back and top should both exhaust air. The bottom or front should pull air in.

 

You want cooler ground air pulling into the machine and flowing through and exiting as it passes the hottest components. If you set your back to pull air in and your top to exhaust hot air you'll likely end up pulling your warm case air back in across the CPU. Aslo keep in mind you'll have your GPU exhausting into the lower portion of the case rear and CPU exhausting via the top. During a gaming session you would add a few extra degrees or more to your CPU temp as you'll effectively raise the ambient temp crossing the CPU cooler.

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Positive pressure (more pressure blowing in than out) is best if you put filters on your intake fans, that way you keep dust in your case to a minimum. Otherwise you have dust being pulled into your case through all the gaps in the case, which gets the dust in hard to reach areas and fills the case with dust, as opposed to positive pressure with filters on the fans where you get little to no dust buildup in the case, only on the filters.

 

What makes it so hard to clean your case every one in awhile? Dust means nada if you clean it out every month..

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What makes it so hard to clean your case every one in awhile? Dust means nada if you clean it out every month..

 

Not always easy to clean, also you should always avoid having to clean electronics as you could easily break some components with ESD. best to get the dust trapped in the fan filters than on your video card. 

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Not always easy to clean, also you should always avoid having to clean electronics as you could easily break some components with ESD. best to get the dust trapped in the fan filters than on your video card. 

Why not? Mine are extremely easy to clean of dust. I use a data vac to blow the dust out weekly. Dust isn't a problem unless you let it cake on. Then you have an issue.

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What makes it so hard to clean your case every one in awhile? Dust means nada if you clean it out every month..

Who said cleaning a case was hard? Depending on how thoroughly you clean out your case it can be considerably harder/more dangerous to clean the entire case than to pull the filters off the fans and clean those.

 

Not to mention, with positive pressure you get no dust buildup around all the little openings in your case, unlike what you get with negative pressure.

 

It comes down to two options:

 

Positive pressure - Only dust you get is on the fan filters - equal cooling potential to negative pressure - costs a few dollars more for fan filters.

 

Negative pressure - Dust over all components and the case itself - equal cooling potential to positive pressure - costs a few dollars less due to no filters required.

 

Unless you can't spare a few dollars, why would you want to clean your case every month vs rarely having to clean it or only cleaning off the filters every month?

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Case I had had fans on the side, front, top, and back.

 

 

Sides...blow fresh air in right on top of the processor/fan.

 

Front...blows fresh air in

 

Top....blows hot air out

 

Back...blows hot air out.

 

also, I put a filter around the intake fans to filter out a lot of the dust.  Picked up a filter roll and make them myself since my case didnt have them nor did the fans I was using at the time.

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Why not? Mine are extremely easy to clean of dust. I use a data vac to blow the dust out weekly. Dust isn't a problem unless you let it cake on. Then you have an issue.

 

How many have an ESD safe DataVac at home ;)

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