Case Pressure

gman

gman

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Graham
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Delving deep here but I was wondering for those who have built their own cases, have you got it setup for positive or negative air pressure? (or the holy grail of neutral).

Also, what kind of airflow setup have you found works best?


One area I'm not sure about is my side fan which is set up as an exhaust to pull the hot air from the MSI 1660 Super. I'm not sure if that's an exhaust at the rear of the card (where the ports are), I don't feel any airflow coming out of it. At the moment I've got my side case exhaust fan directly over that copper part of the heat sink, the theory being that the card's fans are pushing the hot air out from here, which will then be pulled out of the case by my side exhaust fan.


gtx-1660-ti-ventus-xs-design.png
 
I run positive air pressure purely to keep the inside clean. I have 2x 140mm blowing in and 2x 120 blowing out.
 
I went for a case with a straight thru air flow, 2 fans at the front and one at the back.Don't understand what you mean by "air pressure"? that is a new one on me. My very limited knowledge is that the cooler a computer runs the more efficient it is. That is why large business computers are kept in air cooled rooms
 
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Same here, 2 x 140mm in, one x 140mm exhaust. Seems to work fine.
 
realspeed said:
I went for a case with a straight thru air flow, 2 fans at the front and one at the back.Don't understand what you mean by "air pressure"? that is a new one on me. My very limited knowledge is that the cooler a computer runs the more efficient it is. That is why large business computers are kept in air cooled rooms
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Positive pressure is a benefit when you have intake filters that way all air going into the case is filtered.
If you had say only exhaust fans air would come in from everywhere dust included.
 
It's fairly new to me but from what I gather:

Positive is where there's more air being forced in than there is being pulled out by the exhaust fans, so the excess pushed air will find various gaps around the case to escape from.

Negative is the opposite where the exhaust fans are pulling more air in that the intake fans can push in, therefore it will start pulling in air from the various unfiltered gaps around the case which includes dust that will eventually become an insulator.

But there's also the caveat that a mesh filtered fan will have some airflow restriction, even with the static pressure fans. I also have the problem that my case isn't a full tower case, so I'm limited with fan placement. As such I can't use the bottom two fan sections (although the PSU is making use of one) nor can I use the second top fan placement due to the motherboard.

Maybe I need a bigger case.
 
It doesn't matter which you have regarding dust, provided most of the air entering the case comes through any filters fitted. Having a slightly smaller exhaust fan may not really maintain a significant positive pressure inside the case because it won't have to work so hard as the fans drawing air in through a filter. As for cooling, it's much better to think in terms of air flow across components - traditionally the PSU pulls a lot of air through itself, and if that's at the top of the case while CPU and graphics are at the bottom then they will see much less cool air unless you organise the airflow across them.
 
ancient_mariner said:
It doesn't matter which you have regarding dust, provided most of the air entering the case comes through any filters fitted. Having a slightly smaller exhaust fan may not really maintain a significant positive pressure inside the case because it won't have to work so hard as the fans drawing air in through a filter. As for cooling, it's much better to think in terms of air flow across components - traditionally the PSU pulls a lot of air through itself, and if that's at the top of the case while CPU and graphics are at the bottom then they will see much less cool air unless you organise the airflow across them.
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My PSU is at the bottom and temperatures stay surprisingly low, about 32 degrees. I think the fan is setup to suck in cool air from under the case and push it out of the rear vent. It's all pretty self contained.

I've got one intake fan at the front which is filtered and hopefully provides the air flow throughout the case towards all the exhausts. It's pretty unobstructed.

There's a fan fitted sideways on the big cpu heatsink which blows towards the rear exhaust fan.

The fan on top is exhaust to pull out any extra heat from the cpu and also the memory and general case (includes hdd).

The side fan is an exhaust for primarily pulling the hot gpu air out.

I suspect I have negative pressure but there's little dust despite plenty of gaps around the case.
 
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I've been an IT technician for nearly 30 years and being concerned about positive / negative pressure inside a case has never been even a thought in my mind.

Don't worry about it as long as it works and doesn't get hot inside.
 
Yeah but since when did IT technicians care about keeping the inside clean, and components at the lowest possible temperatures. Keeping things clean can have a huge effect on temperatures.
 
Air doesn’t exhaust out of the back of that gpu. Only the ‘blower’ style models do that and as a rule they’re loud and ineffective.

I wouldn’t sweat the positive/negative thing either just have sufficient air flow.
I have 2 x 140mm in and 2 x 120 out.
 
I've been building PCs for thirty years and I try to make them have positive air pressure. My current case has a filtered 180mm fan at the front and a 120mm at the back.
 
Since I have the attention of all the cooling experts.....

I have a PC that has
1. Be Quiet! Dark Rock Pro 4 CPU Air Tower Cooler
2. a pair of be quiet! Silent Wings 3 (120mm) PWM Case Fans
3. a Radeon RX 590

It runs pretty quiet but it's not *really* quiet. Even when it's asleep there is a quiet fan noise.

Speedfan shows that all the drives are nice and cold (35c or less) and the CPU isn't doing anything. The only fan it shows in the GPU fan. As you'd expect, the GPU fan is off. I can turn the GPU fan up and down and hear it spin up but I can't control the other fans. Is there any way I can tell them to spin down a bit? Maybe turn them off when nothing is happening?
 
JonathanRyan said:
Since I have the attention of all the cooling experts.....

I have a PC that has
1. Be Quiet! Dark Rock Pro 4 CPU Air Tower Cooler
2. a pair of be quiet! Silent Wings 3 (120mm) PWM Case Fans
3. a Radeon RX 590

It runs pretty quiet but it's not *really* quiet. Even when it's asleep there is a quiet fan noise.

Speedfan shows that all the drives are nice and cold (35c or less) and the CPU isn't doing anything. The only fan it shows in the GPU fan. As you'd expect, the GPU fan is off. I can turn the GPU fan up and down and hear it spin up but I can't control the other fans. Is there any way I can tell them to spin down a bit? Maybe turn them off when nothing is happening?
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If boot into your bios you should then be able to set a custom fan curve.
 
Or simply set to ‘quiet’ in bios

that sort of cooler and fan set up should be silent. Let us know how you get on.
 
A few developments; my motherboard has a CPU fan header, two 4-pin fan headers and two 3-pin fan headers. I knew the 3-pin ones would run at 100% but they are just too loud, so I went for a Noctua NA-FC1 fan controller which would take the PWM signal from one of my 4-pin headers to control three of the fans and the fourth fan would use the second 4-pin header.

But I ran into a little problem. Unknown to me, those 4-pin headers were voltage controlled so the NA-FC1 was only good in manual mode; which isn't great with this device as it is designed to remain inside the case - so it's awkward to get to the control dial. Time to think...

Well, the solution was staring me in the face. Use the CPU header for the NA-FC1 (I'm powering it from the PSU btw) and connect the CPU fan along with the top and rear exhaust fans to it because they are all directly relative to the CPU temperature anyway and work in tandem. The CPU header is set to keep the fans at 25% unless the CPU temp hits 55°C.

My front intake is connected to the voltage controlled header 1 and set to 50% Auto in BIOS because it's only job is to give the inside some airflow assistance to the exhaust fans and I want to keep it quiet. Auto setting seemed to keep the RPMs a little high.

The side case exhaust fan is connected to the voltage controlled header 2 and also set at 50% Auto in BIOS for quietness. Its job is purely to exhaust the heat from the GPU. Anything which escapes will shoot off up the top exhaust.

(EDIT: Auto seems to have sorted itself out now and doesn't run loud so I prefer to have them be able to increase rpm if necessary).

Here's some numbers from quick 10 minute tests. CPU in stock, but runs about 10°C higher when in o/c mode:

At Idle:
CPU 36°C
Case 24°C
GPU 29°C

FurMark CPU Burner
CPU 57°C
Case 24°C
GPU 29°C

FurMark GPU Stress 4K Ultrawide
CPU 47°C
Case 30°C
GPU 69°C

I'm happy enough with these numbers. I suppose I could stress for longer but the numbers seemed to stabilise at these and I still have the option to increase the fan speeds.

I've also been thinking about a new and better motherboard, my system is eight years old and despite still going strong I quite fancy doing another build. This would mean a new processor which got me looking away from Intel for the first time ever and I spotted the Ryzen 5 3600X. That's incredible performance for the money and I think with the X570 motherboard it is a pretty powerful combination.
 
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geejgee said:
If boot into your bios you should then be able to set a custom fan curve.
Click to expand...
geejgee said:
If boot into your bios you should then be able to set a custom fan curve.
Click to expand...
Brazo said:
Or simply set to ‘quiet’ in bios

that sort of cooler and fan set up should be silent. Let us know how you get on.
Click to expand...

Thanks. Figured out how to get into the BIOS (eventually, Asus website is wrong....all I needed was a wired keyboard).

Tried tinkering with the fan curve and then just set it to "quiet". It's a lot quieter thank you! Still not silent, but better.
 
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