Pure negative pressure for wc

[Warren G]

So putting together my loop, I'm thinking of not having any intake fans and have a couple exhaust fans plus the rads fan pulling. I want to put the case on the floor and avoid dust since I dont have alot of desk space. Would there be any issues? I know the chipset would produce some heat, but hoping the negative pressure would pull it all out. Here's my loop config so far:

Heatkiller 3.0 on the CPU
EK waterblock on a r9 290
Black Ice GT 240 Stealth Rad (top)
Swiftec mcp655 pump
XSPC res
Corsair 650D
Exchaust fans would be 200mm in the front, rad fans at top, and maybe 120mm at rear

 

[mtdewcowboy]

Yep it will fill with dust fast

 

[Crapxxas119]

Exchaust fans would be 200mm in the front, rad fans at top, and maybe 120mm at rear

So you want to use the front fan for exhaust? That is a horrible idea (correct me if i am wrong) for creating a good current in the air (in through front and out through rear). Almost always you should intake on the front and sides, and exhaust on the rear and top.

My suggestion is to keep everything but make the front fan intake. You will still have a negative pressure overall, but at least most of the air will be filtered from the front filter.

 

[m0r7if3r]

If everything but one fan is intake, wouldn't that be positive pressure?

 

[bob4933]

If everything but one fan is intake, wouldn't that be positive pressure?

Nope. More going out than in = negative pressure.



Also, while natural convection and circulation can take a part, forced air circulation is still going to be the best method for either method you are trying to do.

 

[m0r7if3r]

Nope. More going out than in = negative pressure.

Yea, and isn't intake bringing air in? Am I just being dumb?

 

[TheHutchTTU]

If you consider your case a closed system (other than the fans), then there will be no air to be 'exhausted' and nothing to cool your radiators. Since your case is not, the fans will pull air from all the nooks and crannies resulting in a dusty case. Keep the 200mm in the front as an intake fan and the top/rear fans as exhaust.

 

[Waza]

Full negative pressure works great but the dust buildup is ridiculous. If you manage to patch up your case so that intakes are filtered it works ok. For negative pressure to work properly on filtered system you need a lot of passive intake area. Much more than you have exhaust area.

 

[Radeon28]

Yea, and isn't intake bringing air in? Am I just being done?

Mort is right, when more fans are blowing in, that is intake, and positive pressure. When more fans are blowing out, that is outtake, and negative pressure. I think you were both trying to state the same thing, but misread each other.

Regarding pressure, positive pressure is great for dust removal, but can cause small eddies to form in the pockets of your case. Negative pressure creates better airflow (laws of physics states that you can pull fluid more efficiently than you can push it), but the dust collection becomes worse.

Personally, I like to be lightly negative, but that is because my computers are in an extremely dust free environment (thermal electronic lab). If they were home, I'd be running slightly positive. Just remember that if all fans are intake, or outtake, you are making a void of air, and this can be stressful on the fans and lower their lifespan.

 

[EarthDog]

Yep it will fill with dust fast

Assuming no dust covers sure. Otherwise, it only has the cracks to come through...

 

[wagex]

alot of the dust thing really depends on where you live, i only have to clean out dust like once a year and even then, its pretty minimal. but at work i have to do it ever 6 months or so due to the high amount of dust in the air as were a construction company and our building is in the middle of a huge gravel / dirt lot with semi's coming and going all day, and for the most part all my machines and my works machines are all negative pressure. my parents on the other hand live on the other side of town... but they smoke indoors, their pc's get bad.

 

[GTXJackBauer]

Nope. More going out than in = negative pressure.



Also, while natural convection and circulation can take a part, forced air circulation is still going to be the best method for either method you are trying to do.

Mort is right, when more fans are blowing in, that is intake, and positive pressure. When more fans are blowing out, that is outtake, and negative pressure. I think you were both trying to state the same thing, but misread each other.

Regarding pressure, positive pressure is great for dust removal, but can cause small eddies to form in the pockets of your case. Negative pressure creates better airflow (laws of physics states that you can pull fluid more efficiently than you can push it), but the dust collection becomes worse.

Personally, I like to be lightly negative, but that is because my computers are in an extremely dust free environment (thermal electronic lab). If they were home, I'd be running slightly positive. Just remember that if all fans are intake, or outtake, you are making a void of air, and this can be stressful on the fans and lower their lifespan.

You're both on the money.

I like positive pressure in my case since the 900D has a tall unfiltered grill in the back while everything else is. Not that much dust at all in the case, minimal if you will. I have 11 fans blowing in as intake from the front, top and both sides of the bottom and one fan on the backside as exhaust.

 

[madcratebuilder]

Mort is right, when more fans are blowing in, that is intake, and positive pressure. When more fans are blowing out, that is outtake, and negative pressure. I think you were both trying to state the same thing, but misread each other.

Regarding pressure, positive pressure is great for dust removal, but can cause small eddies to form in the pockets of your case. Negative pressure creates better airflow (laws of physics states that you can pull fluid more efficiently than you can push it), but the dust collection becomes worse.

Personally, I like to be lightly negative, but that is because my computers are in an extremely dust free environment (thermal electronic lab). If they were home, I'd be running slightly positive. Just remember that if all fans are intake, or outtake, you are making a void of air, and this can be stressful on the fans and lower their lifespan.

Wouldn't the fan cfm be more important than the number of fans?

Filtered positive pressure gives me the cleanest and coolest temps I've used, I try and run front, bottom, top and side as filtered intake and rear as exhaust. Even with the best of filters you still get some dust after several months of running 24/7.

 

[EarthDog]

CFM is the key, yes... but in a lot of cases, and ALWAYS if the fans are the same model (CFM/SPressure), more fans on either side give you that 'pressure' (use that term so loosely its insane).