Positive case pressure questions?

[dragonbat13]

I saw a website where it talked about keeping a positive pressure on the case to keep dust from making its way into the case. I like this idea but have a couple of questions.

I have a corsair C70 case. Of course if I would have to do this I would have to block off some vents.

What I was wondering is if its worth doing. Also, will it give me cooling headaches? Is it even possible with this large case? The conditions the computer is in is dustier than normal, but not super excessive like a desert. But I hate dust in my equipment and would put out alot of effort to make this work. I would go so far as to tearing down the case and sealing some things off if necessary.

I am not overclocking very much. If anything the CPU which is an ivy 3770K, and I am not going to take it to extremes. The GPU is overclocked from EVGA. Here is everything in the system at this time.

3770K, EVGA GTX670 FTW, FSP 550 watt platinum PSU, H100i cooling system (intake fans). 8G Corsair ddr3 1600, 1T HDD and 256G Samsung 840 Pro. I am using this fan setup: Bitfenix recon fan controller, three phobya nano G-12 120mm fans, Two 120mm fans on the H100i, GPU fan and the fan in the PSU.

What are the odds, if possible at all, to making this positive case pressure idea work on my build?

 

[piasabird]

Isnt this impossible? Air has to come from somewhere. Air cant flow out of the case unless it flows into the case. I could see one air intake with a filter and try to make air flow out of all the other openings. Dust is really evil. I think it might also be a good idea to limit the amount of air flowing through the case.

 

[EarthwormJim]

Positive pressure only keeps dust out of the case as long as you have air filters on all of your fan intakes.

 

[dragonbat13]

I am going to run dust filters on all the intake fans, matter of fact it was a site for fan filters that showed me the idea.

As long as there is more air coming in from the intake fans then going out of the exhausts fans and vents, then the air will be under pressure. Air goes out of the nooks and crannies of the case, keeping dust out.

Ill look for the site I mentioned and post a link.

 

[Blain]

You should run quality intake fans that can provide good "pressure", not simply CFM flow.
Poor quality filtering = more air flow, less filtration
High quality filtering = less air flow, good filtration
That's just the way life is.

 

[tracerbullet]

I am going to run dust filters on all the intake fans, matter of fact it was a site for fan filters that showed me the idea.

As long as there is more air coming in from the intake fans then going out of the exhausts fans and vents, then the air will be under pressure. Air goes out of the nooks and crannies of the case, keeping dust out.

Yep, that's basically all there is to it.

You should run quality intake fans that can provide good "pressure", not simply CFM flow.

Good point. Might help to look at fans / reviews about fans that are intended for use on radiators for water cooling. http://www.anandtech.com/show/6391/120mm-radiator-fan-roundup-part-2-fan-harder

 

[dragonbat13]

I had looked into that a little. The fans I mentioned above were questionable to me. I had not really looked hard at them yet. I did research the controller, and someone on here recommended it.

What are some uses these type of fans in the industry. I figure servers and the like use positive case pressures on a regular basis. Are there any other places to look at?

 

[dma0991]

I run a positive pressure case with 6 intake fans and 1 exhaust at the back. As to whether it can be 100% dust free, its difficult to tell but it will definitely make your life a lot easier when it comes to cleaning time. All intake MUST be filtered to make full use of positive pressure method. As for filters, I recommend Silverstone's magnetic dust filter in 120mm and 140mm sizes. Here's an interesting article about positive pressure.

 

[aigomorla]

I am going to run dust filters on all the intake fans, matter of fact it was a site for fan filters that showed me the idea.

As long as there is more air coming in from the intake fans then going out of the exhausts fans and vents, then the air will be under pressure. Air goes out of the nooks and crannies of the case, keeping dust out.

Ill look for the site I mentioned and post a link.

If u think your case is air tight or air resistant just cuz u screwed on side panels your in for a surpise.

Also the average case with good cable job only has a delta of like 1-2c from inside and outside case.


This entire possivite / negative pressure stuff never sold me.
I always got dust unless i went extreme.

The only time i got it to work as planed was using a very loud high power blower with duct tape on the edges of the case.

 

[tracerbullet]

This entire possivite / negative pressure stuff never sold me.

I sold myself on it when I went from negative (unintentional, just never thought about it) to positive (with filters over the intakes), and finally stopped having to replace DVD burners every 6 months to a year. I couldn't believe how unreliable the dumb things were, but looking back I'm pretty sure I was just pulling dust through them and killing them. No problems since.

 

[dragonbat13]

I am sure the attention to details is what makes the concept work well. For instance I plan on actually swapping out the vented plexi side panel for another piece. Also am going to look into sealing off as much as possible in the mating surfaces of the case panels. For instance, one thing I will have to do is block off all the vented covers for the unused slots in the case. Also am going to see about sealing the intake fans as best I can from the areas outside of the fan area. Like the actuall mounting surface.

 

[dma0991]

You will need some gaps to allow hot air to escape. Completely sealing it will make it even worse as it will trap hot air. Covering the side panel fan slots, that's fine. Covering the PCI slot covers, that's unnecessary.

 

[EarthwormJim]

If u think your case is air tight or air resistant just cuz u screwed on side panels your in for a surpise.

Also the average case with good cable job only has a delta of like 1-2c from inside and outside case.


This entire possivite / negative pressure stuff never sold me.
I always got dust unless i went extreme.

The only time i got it to work as planed was using a very loud high power blower with duct tape on the edges of the case.

The whole point is that your case is not air tight. You have excess filtered air intakes such that all those nooks and crannies are exhausting air, not sucking air in.

I'm pretty sure you're the exception anyway, you have a TON of dust where your computer sits

 

[CurrentlyPissed]

You can't acheive a 100% dustless PC. You could get close by sealing it all off. But then ambient temperatures would be too much. Even more so in multiple GPU situations.

It's not hard to clean a PC. Most intakes now come with filters, just quit being lazy and spray the PC once a month. Takes 10 minutes.

I personally run positive/neutral air pressure. I did the whole positve/negative back and forth thing. Just get your components cool. Don't worry so much about the dust.

My layout on NZXT 820
Front 200M Intake-Fitlers
Bottom RX240 push/pull as intake
Mid-Case 140mm to pull bottom rad intake up
Top RX360 push/pull exhaust
Rear 140mm intake
Side 200mm intake on GPU

Now I could run my 360 up top as intake, but it wouldn't be able to be filtered. So that would incur more dust than just a positive pressure case. So regardless it should be case-by-case. Utilized your filterable areas, and keep the components cool.

This way all heat rises, both rads get cool air, and I sitll maintain a decent exhaust. It won't be dustless. But it'll be close.

 

[Turbonium]

Ok, so wait.

positive pressure = more air inflow than outflow (via case fans)
negative pressure = more air outflow than inflow (via case fans)

But the total inflow = total outflow, regardless, right?

 

[tracerbullet]

But the total inflow = total outflow

Correct

positive pressure = more air inflow than outflow (via case fans)

Not flow, pressure. More pressure forcing air in than pulling it out. Talking about more air going in than out, in my brain and generically speaking, means that the inflow fans blow more air if they were all by themselves, than the outflow fans would if they were all by themselves.

And vice-versa.

People will often just say more inflow than outflow. Correctly it'd be more inflow pressure than outflow vacuum. It's just easy to lop parts of it off since you generally know what is meant. Looking above even I am guilty of it.

 

[Turbonium]

So which one results in less dust settling in the case? Positive pressure or negative pressure? And which one yields lower temps?

I'm guessing whatever the answer, you can't have both less dust and lower temps at the same time.

 

[tracerbullet]

So which one results in less dust settling in the case? Positive pressure or negative pressure? And which one yields lower temps?

I'm guessing whatever the answer, you can't have both less dust and lower temps at the same time.

For me, less dust by far is positive pressure because I am filtering my intake flow. When I had negative pressure, air was coming in from all over the place, including the dust along with it. Including through DVD burners and such which is why I think I lost one every 6 months or so. Since switching no more problems. I filter all my intakes, and make sure they blow harder than the exhausts.

I don't know that temps and dust are mutually exclusive. Best temps probably come from whatever configuration sends the most amount of fresh (aka cool) air over the cpu cooler, whatever setup configuration that happens to be. That may very well be a positive pressure setup. Put filters over the intakes, and win-win.

 

[Blain]

I'm guessing whatever the answer, you can't have both less dust and lower temps at the same time.

Sure you can...
Simply provide plenty of air flow through the PC case (+ or - doesn't matter), just filter all the air going into the case.

 

[DominionSeraph]

Positive pressure only keeps dust out of the case as long as you have air filters on all of your fan intakes.

Don't have to keep it out. One of the benefits of positive pressure is that dust doesn't settle out like negative pressure. Instead of low velocity laminar intake streams from every opening that stay low velocity until the air is within millimeters of the exhaust fan, you have high velocity intake streams that generate turbulent flow within the case and can exhaust that dust-laden air through every crevice.

 

[Blain]

I want to measure the air pressure inside my case vs outside.
What device do I use to determine that pressure?

 

[Socio]

Great thread!

Looks like I am doing it wrong, my case has 3 front fans, 3 top fans and 2 exhaust fans in the rear. I use the 3 front as my inlets with SilverStone FF123 filters, the 3 top and 2 rear as exhaust.

After reading though this thread I am going to filter the three top fans and make them inlets as well for positive pressurization.

 

[tracerbullet]

What device do I use to determine that pressure?

I could probably nab one of these from where I work for a night:

http://www.beamex.com/en

For most though, I wonder if there's a more pedestrian version. Good question.

LOL you could hold some incense near an opening in the case (an opening without a fan) and see if the smoke moves towards or away. It won't give you a variable measurement but you could do an attribute positive / negative.

 

[dragonbat13]

I was thinking about a vacumme gauge for a car, but I dont know if the increments get low enough to check it. You can get vacumme gauges for cars in inches of mercury with vacumme and boost readings, or you can find or make a manometer wich is easier to calibrate than one would think. I dont see why a manometer used with water instead of mercury wouldnt work. I know they use inches of water to flow test cylinder heads. Maybe google "DIY cylinder head flow bench". But I did look at some industrial gauges that could be installed on the case. EXPENSIVE.

 

[Throckmorton]

The whole point of positive pressure is the case doesn't have to be airtight. This is really simple. Put filters on your intake fans and don't worry about using any exhaust fans. If you do use exhaust fans you have to make sure the pressure from them doesn't overpower the intake fans (which are weakened by the filters). So it's easier just to not have any exhausts aside from the graphics card and power supply. Air will still flow out of that big hole behind your CPU just fine because you have positive pressure.

People overthink computer case cooling. It's not a damn nuclear reactor.