What's Best... A Little More Exhaust Or Intake?

[MaTias]

I have a midtower case and i want to know (for cooling) what's best... a little more exhaust or little more intake???

 

Thanks!

[eugenius]

I always say a little more exaust never hurt, I got 1 intake in front, 1 intake on side, 1 exaust on back, 1 exaust on top, and a system blower for my ti4200.

[tkos]

i prefer having more exhaust, it creates a vac, which is what you want

[LobbDogg]

Well essentially you want to create a windtunnel through your PC, and that will cool the most effectively. I currently have 3 intake and 4 exhaust and it keeps pretty cool @ 35 degrees C under load. This is also matched with a good HSF of course. Try probably to keep a 1:2 ratio of intake to exhaust a minimum

[Psywar]

Exaust

[jacobdouds]

4 intake, 3 exhaust, but it all works fine, and 4 exhaust if you count the system blower.

1:1 ratio is better in my opinion, aslong as they are positioned right.

 

Does the fan on the underside of my PSU count as an in our out? It takes air out of the chassis, but into the PSU, and not out of the case...

[exeter_acres]

there really is no correct answer.. I have spent days searching....

 

from a heat standpoint they both work about the same.

I have mine set up with just a bit more intake.. and the reason being is dust....

with more exhaust, dust is pulled into the computer by the negative pressure, with more intake, extra dust is forced out by the positive case pressure.....

 

and also, each case is different.

try both...

put fans in, run it for a while, check temps and then move fans around and try again...

[TypicalSloan]

i dont think u can say how many fans, it should be more like how many cfm of intake and exhaust do i have. Just add up the cfm from all the fans. Ideally in a perfect world the air would go into the case, cool it, then get exhausted. That almost never happens though.

[Propane]

in a perfect world

 

yeah right

[TheEclypse]

ive got 152cfm exhaust, and (soon to have) 135cfm intake.

[Muninn]

From a heat standpoint the exause should be a little higher than the intake about 5:4 ratio or someting.

This is just from a physical science standpoint, in my experience it doesn't matter that much though.

Puting a blowhole in the top helps a bunch tho

 

Muninn

[V8gent]

there sure is a correct answer

 

note: although the term "negative case pressure" is incorrect it suits a valid explanation that everyone can understand.

 

for case temps to remain decently cool, you need to remove the hot air . the ideal acheiveable setup is to have a slight amount of "over-exhaust". air is incredibly effective at filling any potential vacuum and sucks from high pressure to low pressure areas as opposed to it being high pressure being pushed fromj high to low. by setting up a case to have a slight "negative" internal pressure, you're ensuring air flow. of course fan placement will dictate just how good the air flow but at least if you negative in-case pressure you have airflow and that's the primary objective.

 

if you're serious about setting up case air flow up properly then calculate the total CFM being pushed into the case and try and try to get as close as 10% higher CFM air extraction.

 

as I mentioned earlier, the key to keeping case temps down is removing hot air. secondary to that facilitating cool air entry into the case. negative case pressure ensures more air flow than positive pressure because air is much better (faster) at filling vacuums and moving into areas of low pressure than it is than it is moving away from areas of high pressure. as well, positive case pressure can lead to hot air swirls, hot spots per se'. these are not good but depending on where they are, they may not be that bad. still, there