What ratio of fans you should have for positive pressure?

[Garuger]

Heard a lot of possitive pressure but i would like to know the ratio of intakes towards excausts . Of course i know that there should more intakes than excausts but if you have 6 or more fans in a case should 5 be intakes and only 1 excaust? Or should it be 2 intakes towards 1 excaust for example 4 intakes and 2 excausts . Also does it matter were the intakes or excaust fans will be ? for example could you do a reverse flow and still be fine? Like the back of the case be intake and have infront excaust ?I mean as long as the ratio of more intakes than excausts excist it does not matter were the fans will be placed right? 

 

 

Thank you for your time

[Wano97]

3:2 would be positive, I suppose.

[Garuger]

3:2 would be positive, I suppose.

I used more round numbers so it will be a bit easier for placement

[Enderman]

1 to 2 more fans intake than exhaust

[Shaqo_Wyn]

Cases aren't air tight. You can try any config you want or like as long as you avoid doing exhaust only or intake only.

 

When going for positive airflow one or two exhaust fans would already be fine for 4> intake fans. 

 

Up to you which direction you make the airflow go.

[Garuger]

Cases aren't air tight. You can try any config you want or like as long as you avoid doing exhaust only or intake only.

 

When going for positive airflow one or two exhaust fans would already be fine for 4> intake fans. 

 

Up to you which direction you make the airflow go.

Why does it matter were airflow will go?

[spwath]

Why does it matter were airflow will go?

You want it to go towards components.

Also, you want intakes to be filtered

[Victor Yiu]

.

[EmeraldFlame]

For most cases you typically want to keep it as close to even as you can while still maintaining positive pressure (think 51% in, 49% out), although this can obviously differ by case.

So say you have a case with 10 fans that are identical, running at the same RPM, and all have the proper amount of room to breath so the have the same performance. In this case you would most likely want 6 fans in and 4 fans out. Or if you want to go even a little bit more controlled you could hook them up to a fan controller and have 5 in and 5 out, but have the 5 in fans running 100-200 rpm faster than the outs.

[airdeano]

Thank you for your time

 

you cannot look at it from an amount of fans ratio 3 in and 4 out..

 

it is about volume of air CFM. how much air is moved through the fan. but you

will also have to take into consideration that intake fans (filtered) are subject to

restriction from the filter. usually 40-55%. exhaust maybe 10% because of roof

mesh or roof panels.

 

example:

H440 -

3 intake fans @ 75 cfm per fan = 225 cfm (135 cfm corrected for the filter - 40%)

2 exhaust fan (H100i) @ 77 cfm = 154 cfm (138 cfm corrected for mesh - 10%)

1 exhaust fan rear i/o @ 54 cfm (48 cfm corrected for mesh - 10%)

 

135 cfm in and 186 cfm exhaust, this is a negative pressure scenario. no H100i

135 cfm in and 48 cfm exhaust, this is a positive pressure scenario.

[TacticlTwinkie]

I like to keep my case slightly positive in air pressure. I use 4 fans, 2 140mm intake, and 2 120mm exhaust. And I set the fan curves to have them running at about the same speed across the board, so my air pressure should be slightly positive.

[Garuger]

Not necessarily ratios but the amount of air each fan can move in the real world (not looking at the back of the packaging and coming to a conclusion of a $5 fan can move 95CFM). Remember if you filter a fan you diminish its airflow by about 40% depending on the material. Right now I have 3 intakes and 1 exhaust and it's ever so slightly positive.

Yeha i know i cant trust the package only i see also reviews done here https://www.youtube.com/user/CoolingTechnique/videos he has charts etc to show you the real stats.Also cant high static pressure fans solve the filter problem? since they are made for that sort of stuff ?

you cannot look at it from an amount of fans ratio 3 in and 4 out..

it is about volume of air CFM. how much air is moved through the fan. but you

will also have to take into consideration that intake fans (filtered) are subject to

restriction from the filter. usually 40-55%. exhaust maybe 10% because of roof

mesh or roof panels.

example:

H440 -

3 intake fans @ 75 cfm per fan = 225 cfm (135 cfm corrected for the filter - 40%)

2 exhaust fan (H100i) @ 77 cfm = 154 cfm (138 cfm corrected for mesh - 10%)

1 exhaust fan rear i/o @ 54 cfm (48 cfm corrected for mesh - 10%)

135 cfm in and 186 cfm exhaust, this is a negative pressure scenario. no H100i

135 cfm in and 48 cfm exhaust, this is a positive pressure scenario.

I am talking about the same type fans of intake and exccaust . But cant you just put a lower CFM for excaust and higher CFM for intakes to have positive pressure ?.Also dont high static pressure fans and cfm at the same time eliminate kinda the problem with the filter?

I like to keep my case slightly positive in air pressure. I use 4 fans, 2 140mm intake, and 2 120mm exhaust. And I set the fan curves to have them running at about the same speed across the board, so my air pressure should be slightly positive.

I see do you use a fan controller?

You want it to go towards components.

Also, you want intakes to be filtered

Well all the fans would hit the components any way? Expect if you put all of them excaust which would create negative pressure and we dont want that

[TacticlTwinkie]

I see do you use a fan controller?

Sort of. Asus's on board fan control is pretty good.

[Garuger]

Sort of. Asus's on board fan control is pretty good.

From Bios?

[Saient]

Sort of. Asus's on board fan control is pretty good.

 

From Bios?

 

I also use the Asus built in fan controller on my z97-pro. Honestly does everything I need it to do. I use the AI suite rather than bios though, but you don't need to have AI Suite running the whole time.

 

 

On the topic of positive pressure: I have a HAF XB and this thing has holes and grills everywhere. Is it even possibe to have a high pressure when there are so many openings around the case? I've tried some ghetto modding and taped some cardboard over a good majority of the holes, but I actually noticed a slight increase in temperature (though I didn't test this extensively, and also tested without the two 80mm fans)

 

I have two 120mm fans as intake (max 70 cfm), a 120mm as exhaust (max 80 cfm) running at hella low speed, and two 80mm (max 30 cfm) by my drive bays as exhaust just to keep some air moving through the bottom.

[Lingrah]

Linus has a video on this. You want equal air pressure. For though, positive just have more intakes that exhausts.

[Garuger]

Linus has a video on this. You want equal air pressure. For though, positive just have more intakes that exhausts.

Equal is almost imposble to do it

[airdeano]

Also dont high static pressure fans and cfm at the same time eliminate kinda the problem with the filter?

 

your answer is no.

 

static pressure is the exhaust wave (flow) after the fan blade. the filter is in

the front of the fan blade. filtering a high-static fan does the same thing,

decreases the amount of air through the fan.

[TacticlTwinkie]

From Bios?

no. thats only on z97. Asus's z87 boiards do it only from within windows. But it works quite well regardless.

[Garuger]

your answer is no.

 

static pressure is the exhaust wave (flow) after the fan blade. the filter is in

the front of the fan blade. filtering a high-static fan does the same thing,

decreases the amount of air through the fan.

I see so what would  be a good fan filter fan? CFM or static pressure one or a mix of both? ?

[spwath]

your answer is no.

static pressure is the exhaust wave (flow) after the fan blade. the filter is in

the front of the fan blade. filtering a high-static fan does the same thing,

decreases the amount of air through the fan.

In my testing when I put a filter in front of a fan most of the air came out the intake side of the fan

Also, there is nothing wrong with only intakes. The ft05/rv05 have only intake and are the best cooling on the market

[Garuger]

In my testing when I put a filter in front of a fan most of the air came out the intake side of the fan

Also, there is nothing wrong with only intakes. The ft05/rv05 have only intake and are the best cooling on the market

If you only intake wont the system being anaible to dispatch the heat?

[spwath]

If you only intake wont the system being anaible to dispatch the heat?

no

[Garuger]

no

How so?

[spwath]

How so?

Air goes out the vents at top