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Negative to Positive Air Pressure

arrowman1256
By arrowman1256
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So currently my case has negative air pressure, and it seems like its somewhat substantial as well, its a CM Stryker and for the longest time I just assumed it would be positive air pressure. It has (not 100% on the sizes) 2 120mm intake fans at the front and the output fans are 1 120mm at the back near the top and a 140mm fan attached to the top, could I simply turn around the 120mm fan at the back to get positive pressure? Or is there another/better solution I could look at? Any help is appreciated!

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The only benefit of positive airflow is to prevent dust buildup. If any of your intakes aren't unfiltered, it will make little to no difference. 

If you ever need help with a build, read the following before posting: http://linustechtips.com/main/topic/3061-build-plan-thread-recommendations-please-read-before-posting/
Also, make sure to quote a post or tag a member when replying or else they won't get a notification that you replied to them.

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Just now, WoodenMarker said:

The only benefit of positive airflow is to prevent dust buildup. If any of your intakes aren't unfiltered, it will make little to no difference. 

so the big issue is with the Stryker is that there are a ton of unfiltered holes all over the thing, so I would at least like to make it near neutral because I do want to try to cut down on dust buildup, however the intake fans are filtered to answer that question

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Just now, arrowman1256 said:

so the big issue is with the Stryker is that there are a ton of unfiltered holes all over the thing, so I would at least like to make it near neutral because I do want to try to cut down on dust buildup, however the intake fans are filtered to answer that question

Flipping the rear fan for an unfiltered intake will just pull dust in. If your top fan is filtered, you could flip it to intake. 

If you ever need help with a build, read the following before posting: http://linustechtips.com/main/topic/3061-build-plan-thread-recommendations-please-read-before-posting/
Also, make sure to quote a post or tag a member when replying or else they won't get a notification that you replied to them.

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1 minute ago, WoodenMarker said:

Flipping the rear fan for an unfiltered intake will just pull dust in. If your top fan is filtered, you could flip it to intake. 

yea the top fan is filtered, which honestly i thought was odd for an output, but do you think that may make it way to much of a positive pressure due to it being a 140mm?

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Just now, arrowman1256 said:

yea the top fan is filtered, which honestly i thought was odd for an output, but do you think that may make it way to much of a positive pressure due to it being a 140mm?

No, cases aren't closed systems. 

If you ever need help with a build, read the following before posting: http://linustechtips.com/main/topic/3061-build-plan-thread-recommendations-please-read-before-posting/
Also, make sure to quote a post or tag a member when replying or else they won't get a notification that you replied to them.

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1 minute ago, WoodenMarker said:

No, cases aren't closed systems. 

okay fair enough and just curious would flipping it make a major effect on the case considering its almost literally right next to the back case fan? basically as in would the air coming in from it just immediately be vented out?

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Just now, arrowman1256 said:

okay fair enough and just curious would flipping it make a major effect on the case considering its almost literally right next to the back case fan? basically as in would the air coming in from it just immediately be vented out?

No.

If you ever need help with a build, read the following before posting: http://linustechtips.com/main/topic/3061-build-plan-thread-recommendations-please-read-before-posting/
Also, make sure to quote a post or tag a member when replying or else they won't get a notification that you replied to them.

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If you have enough case ventilation the temperature differences between positive pressure and negative pressure will be minimal, and the dust difference between positive pressure and negative pressure (assuming you have filtered intakes) will be substantial. If you think your case has enough passive ventilation, then there is no reason to be worried about any amount of positive pressure. I know in my Thermaltake Versa N21 case it has poor ventilation, and I was running 4 intakes and 1 exhaust. things would get quite toasty in there.

 

 

Also, keep in mind that fan count is not what decides pressure. CFM is what decides pressure (the amount of air flow). You could always just turn up the RPM on your intake a bit, and turn down the RPM on your exhausts a bit in order to make it positive pressure, without having to change anything around.

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1 minute ago, Zyndo said:

If you have enough case ventilation the temperature differences between positive pressure and negative pressure will be minimal, and the dust difference between positive pressure and negative pressure (assuming you have filtered intakes) will be substantial. If you think your case has enough passive ventilation, then there is no reason to be worried about any amount of positive pressure. I know in my Thermaltake Versa N21 case it has poor ventilation, and I was running 4 intakes and 1 exhaust. things would get quite toasty in there.

 

 

Also, keep in mind that fan count is not what decides pressure. CFM is what decides pressure (the amount of air flow). You could always just turn up the RPM on your intake a bit, and turn down the RPM on your exhausts a bit in order to make it positive pressure, without having to change anything around.

Yea I thought about adjusting the RPMs on the fans, though I think for me to do that the way its currently set up I would have to plug the fans directly into the mobo as opposed to how they are now being plugged into the front controller which I can use to adjust all of their fan speeds simultaneously, though im not 100% on that.

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2 minutes ago, arrowman1256 said:

Yea I thought about adjusting the RPMs on the fans, though I think for me to do that the way its currently set up I would have to plug the fans directly into the mobo as opposed to how they are now being plugged into the front controller which I can use to adjust all of their fan speeds simultaneously, though im not 100% on that.

Depends on the kind of fans and the kind of controller. But if you don't want to do that, you could always just flip your 140 around to intake. I'm sure it wouldn't be a big deal.

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How about just removing or disconnection the top 140?  Assuming your temperatures remained OK, that is.

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1 hour ago, ThomasD said:

How about just removing or disconnection the top 140?  Assuming your temperatures remained OK, that is.

Or changing the speeds of intake (faster) and exhaust (slower) fans.

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