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Positive Pressure?

post #1 of 17
Thread Starter 
Hello. I am confused on how many fans I should have and how I should position them in my case.

I have read that positive pressure is the best way to go if you want as little dust as possible. How should I set this up??

I can mount two 140mm on the front of my case, but since I am holding my SSD and HDD in a tray on the bottom, should I still get a fan for the bottom?

For the side, I was debating whether I should cut off the grill. I am not worrying about air going to the GPU since temps are 34 at idle, but would it benefit anything else? My PSU is facing down.

I have a 212+ with one fan currently (pull) and plan on getting a second one for pushing. Would it be better to have a rear fan without a pull or have both of them there?

As for the top I have no clue. It can mount three 140mm (or maybe 2 140mm and one 120mm) and have been told before this creates a problem. If I put a fan near the back end on top would it be taking any air? If I put one in the middle would that disrupt the airflow? If I put one in the very front I think that if I put it for an intake it could go to the 212+.

And one final thing to ask, would my intakes need to be higher CFM or would my exhausts need to be?

That is a lot of writing.. thanks for those who will help and actually read that.
post #2 of 17
I have the Lancool PC-K62 case and I changed the fan configuration around to have the top 2 fans as intake. I have modded the front to include a 2nd fan so the bottom fan is intake and top front fan is exhaust. The Antec 920 CPU cooler is also on exhaust. I know alot of people say that top mounted fans in a case should be exhaust but I have found that with the config I have the amount of dust in the rig is virtually zero. Very happy with the cooling temps also. Just my 2cents.gif

Note - 2x140mm fans in the roof as intake, 1x120mm front as intake and 1x120mm front as exhaust, 2 x 120mm fans in push pull on the radiator as exhaust.
Edited by K62-RIG - 10/25/12 at 5:24pm
post #3 of 17
    
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post #4 of 17
Thread Starter 
Thanks for the help guys. I thought about using this setup:



My idea:

Two front intake; one to cool SSD and HDD, and other to go to the CPU/GPU

Side: Still debating whether to get one. My GPU temps are fine. I don't think they would really help CPU temps though. If I end up not using it, I want to cut out the grill and actually make a window.

Top: I didn't know if I should have added anything in the middle and end, but I thought if I remove my optical drive, can I just put a fan at the very front as intake so the CPU can get fresh air? But then wouldn't the foam on the dust filters interfere a lot?

Back: Should I have anything or just let air flow naturally?
post #5 of 17
positive pressure by itself does NOT reduce dust.

positive pressure WITH AIR FILTERS on intake fans does reduce dust.

intake fans WITH filters have their rated CFM cut as much as 50% or more. so be mindful of that fact when estimating case pressure.

just trying to clear up some misconceptions about the term positive pressure.
post #6 of 17
Quote:
Originally Posted by Firelance View Post

My PSU is facing down.

If your case is mounted in a hard surface, the better placement is the PSU fan mounted down.
This way the fan will intake flesh air from the bottom to the psu and exhaust the heat on the back.
If your case has a removable dust filter, you can still clean the dusty.

But if your case is mounted on a carpet or you have problem with dust you could mount the PSU fan facing up.
This way the PSU fan will intake the air inside the case and exhaust the heat on the back.

For the psu is better to intake the flesh air outside the case instead of to intake the warm air inside the case.
Quote:
Originally Posted by Firelance View Post

I can mount two 140mm on the front of my case, but since I am holding my SSD and HDD in a tray on the bottom, should I still get a fan for the bottom?

If you could mount the bottom fan this fan would help the SDD and HDD cooling.
If you can't mount this fan no need to worry about it.
Quote:
Originally Posted by Firelance View Post

For the side, I was debating whether I should cut off the grill. I am not worrying about air going to the GPU since temps are 34 at idle, but would it benefit anything else?

There's dust filters like these from Akasa:

120mm - Akasa GRM120-AL01-BK
http://www.frozencpu.com/products/14764/ffi-91/Akasa_Aluminum_120mm_Fan_Filter_-_Black_GRM120-AL01-BK.html

140mm - Akasa GRM140-AL01-BK
http://www.frozencpu.com/products/14765/ffi-92/Akasa_Aluminum_140mm_Fan_Filter_-_Black_GRM140-AL01-BK.html
Quote:
Originally Posted by Firelance View Post

I have a 212+ with one fan currently (pull) and plan on getting a second one for pushing. Would it be better to have a rear fan without a pull or have both of them there?

I'm using the 212+ push pull with the rear fan.
This rear fan helps to exhaust the hot air outside the case.

If you have any cons about the rear fan check this article.
http://www.hardwaresecrets.com/article/How-the-Case-Rear-Fan-Improves-CPU-Cooling/1416
Quote:
Originally Posted by Firelance View Post

And one final thing to ask, would my intakes need to be higher CFM or would my exhausts need to be?

I believe you no need to worry about it.
But you can try to have same or more intake fans than the exaust fans.
Quote:
Originally Posted by Firelance View Post

As for the top I have no clue. It can mount three 140mm (or maybe 2 140mm and one 120mm) and have been told before this creates a problem.
If I put a fan near the back end on top would it be taking any air? If I put one in the middle would that disrupt the airflow?

I've heard from a few guys that too many fans means "moar" fans. LOL
http://www.overclock.net/t/1305446/different-testing-scenarios-coolermaster-hyper-212-graph-data-findings-recommendations

But I believe that the top fans wouldn't harm your system.
I never heard any overheat issues related to the top fans.
I also believe you no really need to place the all top fan mounts.
There's cases that only supports one or two top fan mounts.
Edited by edsai - 10/25/12 at 6:50pm
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post #7 of 17
Sorry, double post.
Edited by edsai - 10/25/12 at 6:50pm
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Core I5 3570K Asus P8Z77-V LX Corsair Vengeance 8GB 1600 MHz DDR3 Seagate 2T 7200 RPM SATA 3 
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post #8 of 17
Thread Starter 
Rep for both of you guys.

I still need help on whether the picture I posted is good though. I know the only way to know if the setup is good is if I test it out myself but first I need to clarify my setup.

And are you also positive on the CFM thing? I swear reading somewhere that lower CFM should be in front and higher as exhaust..
post #9 of 17
Quote:
Originally Posted by Firelance View Post

And are you also positive on the CFM thing? I swear reading somewhere that lower CFM should be in front and higher as exhaust..

ok, lets use that principal you described..
you eat 2-pounds of chocolate and poop 5-pounds.. your net mass is off-set 3-pounds "negatively"
you eat 2-pounds of cheetos and poop 1-pound.. your net mass is off-set 1-pound "positively"

fans rated 90cfm, you have two of them, so that 180cfm. got an air filter, reduce that to 90cfm (from 50%
reduction from psyclum description). exhaust rated 75cfm.. you are positive 15cfm, so you have more
coming in than going out.

the excess escapes vents, slots, cracks and any opening outward.

hope this helps..

airdeano
post #10 of 17
Quote:
Originally Posted by airdeano View Post


you eat 2-pounds of chocolate and poop 5-pounds.. your net mass is off-set 3-pounds "negatively"
you eat 2-pounds of cheetos and poop 1-pound.. your net mass is off-set 1-pound "positively"

i may have to save this quote biggrin.gif
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