Negative or positive pressure? Does it matter?

[lexluthermiester]

@AusWolf
There's been a lot of chatter about dust collection and negative vs positive pressure. Let's address those for a brief moment.
1. The dust. You're going to get some into your case. It is unavoidable, full stop, end of story. Reside yourself to the fact that you will have to do cleaning from time to time.(I'm betting you already knew this)
2. The differences between "negative" and "positive" air pressure in a case are measured in mere fractions of a percent of PSI. It's not worth being concerned over, at all, ever.

Now that we have those two points out of the way, your biggest concern should always be airflow. You want to configure you fans in your case so that there is always a steady and consistent flow of fresh air coming into the case and a similar flow going out. Thermal dynamics would posit that you obey the simple law that hot air rises and cool air descends. So naturally, you want configure your fans to be pulling fresh air from a point lower in the case and exhausting it out through a higher point in the case. However, if the airflow is strong enough, you can have airflow doing the opposite of what I just described and you'll be fine. But as a general rule you want to let the forces of nature work for you instead of fighting against them.

Configuring your fans to attain optimal airflow might be easy-breezy or it might take some experimentation. Just depends on your case and what you put in it.

Hmm... I've never considered something like this. It sounds silly, but interesting.

That's because it is very silly. Not worth your time..

 

[Ferd]

As far as dust concerns go , in both scenarios you are pulling air from the room into the case , so it’s coming in regardless of the chosen path

 

[Shrek]

That is where the speed comes in; slow air cannot carry as much dust as fast.

 

[AusWolf]

@AusWolf
There's been a lot of chatter about dust collection and negative vs positive pressure. Let's address those for a brief moment.
1. The dust. You're going to get some into your case. It is unavoidable, full stop, end of story. Reside yourself to the fact that you will have to do cleaning from time to time.(I'm betting you already knew this)
2. The differences between "negative" and "positive" air pressure in a case are measured in mere fractions of a percent of PSI. It's not worth being concerned over, at all, ever.

Now that we have those two points out of the way, your biggest concern should always be airflow. You want to configure you fans in your case so that there is always a steady and consistent flow of fresh air coming into the case and a similar flow going out. Thermal dynamics would posit that you obey the simple law that hot air rises and cool air descends. So naturally, you want configure your fans to be pulling fresh air from a point lower in the case and exhausting it out through a higher point in the case. However, if the airflow is strong enough, you can have airflow doing the opposite of what I just described and you'll be fine. But as a general rule you want to let the forces of nature work for you instead of fighting against them.

Configuring your fans to attain optimal airflow might be easy-breezy or it might take some experimentation. Just depends on your case and what you put in it.

That's where my question comes in.
I'm wondering whether I'd be better off 1. leaving my system as it is (2x 12 cm intake, 240 mm AIO exhaust), or 2. buying 2x 14 cm (potentially also higher rpm) intake fans, or 3. buying a 280 mm AIO as exhaust.

As far as dust concerns go , in both scenarios you are pulling air from the room into the case , so it’s coming in regardless of the chosen path

That is where the speed comes in; slow air cannot carry as much dust as fast.

Guys, please, just one more time: I'm not concerned about dust! It goes wherever air moves. Period.
I'm concerned about cooling efficiency and noise (especially GPU-wise). If you're replying to my OP, can you please give a relevant answer according to your experience and/or best knowledge? Thanks.

 

[ThrashZone]

Hi,
Check peoples spec's before you give them to much credit
Clearly Lex is speeking from a non overclocking perspective.

 

[AusWolf]

Hi,
Check peoples spec's before you give them to much credit
Clearly Lex is speeking from a non overclocking perspective.

That's fine, I don't overclock, either. I just want my PC to run as cool and quiet as possible.

 

[Ferd]

That's where my question comes in.
I'm wondering whether I'd be better off 1. leaving my system as it is (2x 12 cm intake, 240 mm AIO exhaust), or 2. buying 2x 14 cm (potentially also higher rpm) intake fans, or 3. buying a 280 mm AIO as exhaust.



Guys, please, just one more time: I'm not concerned about dust! It goes wherever air moves. Period.
I'm concerned about cooling efficiency and noise (especially GPU-wise). If you're replying to my OP, can you please give a relevant answer according to your experience and/or best knowledge? Thanks.

Sorry about the frustration ...

As far as cooling I agree with this ,

@AusWolf
There's been a lot of chatter about dust collection and negative vs positive pressure. Let's address those for a brief moment.
1. The dust. You're going to get some into your case. It is unavoidable, full stop, end of story. Reside yourself to the fact that you will have to do cleaning from time to time.(I'm betting you already knew this)
2. The differences between "negative" and "positive" air pressure in a case are measured in mere fractions of a percent of PSI. It's not worth being concerned over, at all, ever.

Now that we have those two points out of the way, your biggest concern should always be airflow. You want to configure you fans in your case so that there is always a steady and consistent flow of fresh air coming into the case and a similar flow going out. Thermal dynamics would posit that you obey the simple law that hot air rises and cool air descends. So naturally, you want configure your fans to be pulling fresh air from a point lower in the case and exhausting it out through a higher point in the case. However, if the airflow is strong enough, you can have airflow doing the opposite of what I just described and you'll be fine. But as a general rule you want to let the forces of nature work for you instead of fighting against them.

Configuring your fans to attain optimal airflow might be easy-breezy or it might take some experimentation. Just depends on your case and what you put in it.


That's because it is very silly. Not worth your time..

the way it works is very basic , and you always want nature to work for you

 

[ThrashZone]

That's fine, I don't overclock, either. I just want my PC to run as cool and quiet as possible.

Hi,
11700k boost clock is overclocking lol

 

[freeagent]

My solution to dust?

DataVac Electric Duster - Better Than Compressed Air | MetroVac

If you have one.. when my fans spool up it sounds like that, minus a couple db

 

[lexluthermiester]

2. buying 2x 14 cm (potentially also higher rpm) intake fans

This. The simple math says you'll get better airflow as long as you go with fans that offer at least 1200rpm.

I'm not concerned about dust! It goes wherever air moves. Period.

This. Well said.

Check peoples spec's before you give them to much credit

I currently have 6 different PC's, two of them OC'd. There is no room in the "specs" for all of them so I put the tablet specs in to shut people up about it and to help others make fools of themselves...

Clearly Lex is speeking from a non overclocking perspective.

Wrong. I am speaking from a science based experience perspective. Kindly keep your condescending remarks to yourself and learn how to spell..

 

[MentalAcetylide]

I shared some videos in case someone is new to the topic and wants to know what's going on. What's so lol about that?


That's good advice, but again...

Everyone: Dust is not my issue! I want to make my PC as cool and quiet as possible. I want to know what setup would be best especially for GPU thermals. That's it. Please stop telling me about dust. Thank you.

My suggestion would be the same, regardless. There's really no good reason that I can think of in trying to achieve a strongly positive or negative airflow in the case if you want sufficient removal of warm air while replacing it with cooler air.

 

[ThrashZone]

That's because it is very silly. Not worth your time..

Hi,
This is not science
More like ending with a joke lol

God forbid making all fans intake and removing the pci-e covers is some sort of taboo thing not worth trying

 

[Jetster]

As far as dust concerns go , in both scenarios you are pulling air from the room into the case , so it’s coming in regardless of the chosen path

nope
With negative pressure its pulling the air in threw any available hole. USB slot, holes in the metal case, DVD drive. The kinda of hole you don't want dust in.
Positive pressure does not "pull air in" it pushes it in threw filters right where you want it to enter. Big difference. No dust

I've said this before. I live in a high humidly area. There is good and bad with this. Good; no static electricity at all. Bad; dust sticks to every part and is difficult to remove. I always run positive pressure. Many fans in 1 or none venting

lexluthermiester, its not silly. I have posted pics before of the difference. But if I need to I can do it again ​

​

 

[ThrashZone]

nope
With negative pressure its pulling the air in threw any available hole. USB slot, holes in the metal case, DVD drive. The kinda of hole you don't want dust in.
Positive pressure does not "pull air in" it pushes it in threw filters right where you want it to enter. Big difference. No dust

Hi,
Guessing this is a typo
Pull through filters is better.

 

[Deleted member 24505]

I have always read from lots of sources that positive is better, as Jetster said, you end up sucking dust in through USB ports, possibly even the ones in the boards i/o, and every crack in your case.

 

[lexluthermiester]

With negative pressure its pulling the air in threw any available hole. USB slot, holes in the metal case, DVD drive. The kinda of hole you don't want dust in.
Positive pressure does not "pull air in" it pushes it in threw filters right where you want it to enter. Big difference. No dust

I have always read from lots of sources that positive is better, as Jetster said, you end up sucking dust in through USB ports, possibly even the ones in the boards i/o, and every crack in your case.

Except that fluid physics dictate that any space a fluid can travel through, it will travel in all directions, thus dust suspended in that fluid will be carried in either direction, filtered or not. Most PC filters fail to capture smaller, more damaging particles that get into bearings and optics. The only thing PC filters do is to trap larger particles that will otherwise be unsightly. But as they do, they have the effect of restricting airflow, which is bad.

So, lose the air filters and forget about positive & negative pressure. Focus on airflow and you will swiftly discover better cooling as a result.

 

[Jetster]

Better is not the right word. There is pro and cons with both. Positive pressure does run hotter and moved air slower

Except that fluid physics dictate that any space a fluid can travel through, it will travel in all directions, thus dust suspended in that fluid will be carried in either direction, filtered or not. Most PC filters fail to capture smaller, more damaging particles that get into bearings and optics. The only thing PC filters do is to trap larger particles that will otherwise be unsightly. But as they do, they have the effect of restricting airflow, which is bad.

So, lose the air filters and forget about positive & negative pressure. Focus on airflow and you will swiftly discover better cooling as a result.

Fluid will not travel up stream. Not that I'm aware of . And I'm not concerned with 50 micron dust. Does dust get threw yes. But not as much, way less

Believe it or not that is like 2 months. Fn cat

 

[Deleted member 24505]

Have to say, jays video was much better than the tit linus's video. I'm gonna have a juggle around of my setup tomorrow and see what it's like.

 

[Shrek]

With negative pressure its pulling the air in threw any available hole. USB slot, holes in the metal case, DVD drive. The kinda of hole you don't want dust in.
Positive pressure does not "pull air in" it pushes it in threw filters right where you want it to enter. Big difference. No dust

Good point, with filtering one wants to catch the air as it comes in, so then positive pressure is the way to go.

 

[ThrashZone]

Good point, with filtering one wants to catch the air as it comes in, so then positive pressure is the way to go.

Hi,,
Yep filter are a wonderful thing
Case makers make and include them for a reason = use and keep them clean.
Get rid of cats lol

 

[AusWolf]

Sorry about the frustration ...

As far as cooling I agree with this ,



the way it works is very basic , and you always want nature to work for you

There's no frustration at all. Only a failure to comprehend why some people still keep thinking that I'm bothered by dust even though I've said multiple times that I'm not.

People! I have dust filters. I also acknowledge the fact that dust finds its way into your case regardless of your cooling setup. I don't give a rat's arse about this side of the topic. What I want is cooling and silence. Can you please, please keep this in mind before commenting, or at least not direct your comment towards trying to help me? (as giving advice about dust is clearly not helping me - it might help others, though) It would be very much appreciated.

This. The simple math says you'll get better airflow as long as you go with fans that offer at least 1200rpm.

Now that's an interesting point. My current intake fans max out at about 1200 rpm. Maybe I should look for faster ones?

My suggestion would be the same, regardless. There's really no good reason that I can think of in trying to achieve a strongly positive or negative airflow in the case if you want sufficient removal of warm air while replacing it with cooler air.

Thanks for the tip. I'm trying exactly that. My current setup is fairly balanced, but clearly not powerful enough, demonstrated by the fact that I can drop a good 6-8 °C off of both the CPU and GPU by just removing the side of the case. The ideal situation would be replacing my 240 mm AIO with a 280 mm unit, and my 12 cm intake fans with 14 cm ones, but I'm afraid all these won't fit at the same time due to how close the front panel is to the rest of the case. So it's either bigger AIO with bigger fans, or just bigger intake fans at the front, but not both.

 

[Shrek]

Except that fluid physics dictate that any space a fluid can travel through, it will travel in all directions, thus dust suspended in that fluid will be carried in either direction.

Unless it is dropped first.

There was an experiment by Pasteur to show bacteria exist. He heated soup but left it connected to the air by a curved tube; the bacteria collected at the bottom of the curve and the soup did not go bad.

OK, this is getting a bit crazy; the only point I am making is that the slower the flow the less dust is suspended.

I wonder if one could make a cyclone dust trap based on this principle (a bit like a Dyson vacuum cleaner).
Amazon.com: Cyclone Dust Collector Dust Collection Dust Separator Shop Vac Accessories (Green) : Tools & Home Improvement

Ah, the OP is not interested in dust entrapment; I stop.

 

[lexluthermiester]

Fluid will not travel up stream. Not that I'm aware of .

Air is a fluid and yes it does given the right force.

Now that's an interesting point. My current intake fans max out at about 1200 rpm. Maybe I should look for faster ones?

Yes. If you want better air flow and you're willing to live with a bit of extra noise(not a lot), then faster fans would be a good investment.

People! I have dust filters.

Seriously, lose the filters. Your airflow, and thus cooling, will dramatically improve as a result. If you're worried about dust, get one of these and use it to blow out your system once a month(or whenever needed depending on your environment);

https://www.amazon.com/Compressed-MECO-High-Pressure-Computer-Keyboard/dp/B082XR3987

Make sure you vacuum your house every two weeks at least and you'll have minimal dust collect in your PC. Again, speaking from experience.

 

[Shrek]

Seriously, lose the filters. Your airflow, and thus cooling, will dramatically improve as a result.

I agree, which leads to the thought of an electrostatic filter (the sort used on power station stacks) which should have very little restriction;
or the cyclone collector.

But if we are off topic, I'm happy to stop.

I find all this very interesting, but feel that may not be the case for everyone.

 

[AusWolf]

I agree, which leads to the thought of an electrostatic filter which should have very little restriction.

But if we are off topic, I'm happy to stop.

I find all this very interesting, but feel that may not be the case for everyone.

It's not off topic as long as you don't mean it as an answer to my question.

An electrostatic filter would be interesting. Does it exist? (sorry, I'm not very knowledgeable about filters)

Air is a fluid and yes it does given the right force.


Yes. If you want better air flow and you're willing to live with a bit of extra noise(not a lot), then faster fans would be a good investment.

Seriously, lose the filters. Your airflow, and thus cooling, will dramatically improve as a result. If you're worried about dust, get one of these and use it to blow out your system once a month(or whenever needed depending on your environment);

https://www.amazon.com/Compressed-MECO-High-Pressure-Computer-Keyboard/dp/B082XR3987

Make sure you vacuum your house every two weeks at least and you'll have minimal dust collect in your PC. Again, speaking from experience.

I have one of these. I'll check out some new fans, thanks.