Case Cooling/Pressure Question

Rafaeleh

Rafaeleh

Rafaeleh

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Joined
7 Jul 2022
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2
Location
Europe
I've got a phanteks p400a and I am thinking of upgrading my fans since i only have the stock ones installed.

This is what i intend on doing:

ZUOePnA.jpeg

Theoretically i'd get 208 CFM of intake and 206 CFM of exhaust. The front fans are 140mm airflow fans, the top ones are 140mm static pressure fans and the back one is a 120mm static pressure fan.

My thinking is as the case has a mesh front panel the intake will be slightly lower, but as the top fans also have a dust filter on top those will also have a lowered exhaust and as the top filter has smaller holes, than the front mesh panel, and is closer to the actual fans i am guessing they will have a greater decrease in CFM than the front fans thus creating positive pressure in the case ?


My question is with this configuration will i theoretically get slightly positive pressure and will the air inside the case flow well?
 
Your theory is flawed. Intake venting is more restrictive than exhaust, and your fan cfm specs are totally free airflow at full speed. I doubt you will be running full speed, so airflow will be much less compounded by airflow resistance of grill, filter, cables, etc.

What I've found over the years is filling front venting with fans and blocking any openings not covered by them is all that's needed .. as in no exhaust fans required. This means only intake fans generating noise .. usually meaning a quieter system as well. Running both intake and exhaust fans is similar to running push/pull on radiator or cooler .. at same fan speed push/pull moves a little more air, but more fans make more noise, so at same by increasing case with only intakes to same dB as case with both intake and exhaust fans ends up being same temps. This is not 100%, but it's usually the case (no pun). Rare case (no pun) exception is when use of exhaust fan helps create a intake air flow path that flow cool air to component better than without exhaust fan.

Reason for blocking openings is air fans push into case flows toward lower pressure areas in case .. and area between front grill and fans is lowest pressure area, so instead of all air flowing on thru case some (often quite a bit) is leaking around thru holes in fan mounting panel into area between fans and front of case and going in circles.
 
I see i was having the wrong idea, that actually makes a lot of sense. Will try what you've suggested and also block the openings that now with further inspection it seems to have quite a few where air could be circling around.

Thank you so much for the explanation ! Greatly appreciate it.
 
No problem, glad to be able to help.
The science of airflow is "fluid dynamics". For air to move into case there has to be same amount of air moving out of case.
Think of case as a box with vents being holes in box under water in a big tank. If we have 2x holes on one side and 3x holes on other of box and put propellers in 2 on one side the water they move into box will be flowing out of box thru the other 3 holes.
 
I have the evolv x with a artic freezer 2 420 mm in the front with 3 noctua 3000rpm fans, 2 on top as intake and 1 on the rear, I do have demifex on top and front as they keep the dust down and its been great so far.
 
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