Positive case pressure question

[hipster]

I'll be using a larger mid-tower http://www.compusa.com/products/product_info.asp?sid=3FEE1D0061E3617F&product_code=300256&pfp=BROWSE
P4C, with 2 Panaflow H2 80mm 40cfm upfront with grids from case removed and 1 Vantec stealth 120mm 53cfm on rear with case grid not removed "yet" and a stock P4 cpu HSF. Do you think the air flow design will work out OK?

 

[CCW]

If you have case fans that asre only blowing out, air will find its way back into the case due to negative pressure, the air will move to the area of negative pressure so you will get cool air into the case. This is infact why we have wind, its air moving from an area of high pressure to low pressure. If you only have air blowing in, the air will become trapped, it wont be able to easily escape and the ambient case temperature will rise. Ideally, you need equal air flow in as out, if this is not possible, make sure more air is blowing out as air will always replace the air being pushed out.

Craig

 

[hipster]

Thanks CCW, I thought positive air pressure was desired (more air entering thru fans in front) to run cooler? I suppose if that is not the case then I should reduce my front fan cfm intake either by a fan controller or by installing lower cfm fans. In which I also have a Panaflow L1a 24cfm fan coming & I could just substitute 1 of the H2's with if needed. BTW I will also have the fan on my Fortron psu exhausting air as well so I guess I should have a good mix to work with. Wwwhat is the best way to check and moniter? ( no side window) Use Asus probe to watch temp's?

 

[Jognt]

WAIT WAIT

you want so-called "positive pressure" (though it isnt really pressure tbh)

if you have got less air entering the case than you have air leaving, then air AND dust will creep into your case via any hole they can find, if you got more air entering then the holes through which dust would enter air would now come out of there, thus make sure no dust enters your case (or less..)

have the two panaflos as intake in the front, and have the vantec as exhaust in the back, should work out pretty good, because the PSU fan is also an exhaust

good luck

to quote the fanman

keep your flow up and temps down

 

[hipster]

Thanks Jognt.

 

[CCW]

Well wind in the Earths atmosphere is caused by air rushing from a high pressure (postive0 area to a low pressure (negative) area so if you have all of your air being exhausted from the case there will be negative pressure in there cauisn air to move into the case (usually through cracks in it)

 

[craneage2001]

My rig's a bit of an exception...I run two 80mm fans out the back and one in from the side... throw in the PSU and I run with a moderate amount of negative pressure. I cut a hole in the side window right over the CPU and ran a round duct right down to just above the fan on the HS. The negative pressure helps the fan draw in the fresh air from outside and the net result was about a 5°C drop in temps. Consequently, I have to keep an eye on the dust, but it's never a problem where I keep my PC up rather than on the floor. I clean it out every month or so and it's never bad at all.

 

[mccoyn]

I believe fans run more effectiently with close to neutral pressure. That means more airflow with less noise.