More fans blowing in or sucking out?

Oj · Post by Oj » 20 Mar 2006, 13:31

Just a quick question: when setting up your system with x amount of case fans, should you have more fans blowing air out (negative pressure) or sucking air in (possitive pressure)? Everyone I ask seems to have a different answer.

WiK1d · Post by **WiK1d** » 20 Mar 2006, 13:40

You should try to keep it balanced...

2 in 2 out...
15 in 15 out...

But I find the best way for me is having 1x120mm blowing from the back of the case and 1x120mm extracting in the front...

Oj · Post by Oj » 20 Mar 2006, 13:50

All fans will be 8cm, and there are 3, there will be 5. So it has to be uneven...

PureFire · Post by **PureFire** » 20 Mar 2006, 13:53

ive been told both before, but im thinking that you want more air moving inside to keep ambient temp down.

SLIP · Post by **SLIP** » 20 Mar 2006, 14:24

From my personal experience a have noted that If I let all my fans suck air out my case stays the coolest.

Please note that I have tried various combinations with my fans..., and if they are all sucking out there has to be a vent in your case where the new air can flow back in....

Currently I have one 120mm and 2x 80mm fans sucking out and it works like a bomb...

...and if you want decent cooling, try to stick to 80mm fans and bigger.....

RuadRauFlessa · Post by **RuadRauFlessa** » 20 Mar 2006, 14:25

Lets put it this way. Your case is not airtight. You have no fins on the inside to properly direct airflow. Then it does not matter. Make it posetive although you won't get it to that as my first point was that your case is not airtight. Any pressure you do create will simply leak out of the case faster than the diff a single neg fan will do.

SLIP · Post by **SLIP** » 20 Mar 2006, 14:41

The hotter the pc is the more fans you gonna need...

..and don't forget...I have one of these

in my machine aswell as

on my HDD.....

RuadRauFlessa · Post by **RuadRauFlessa** » 20 Mar 2006, 14:47

Now now SLIP this is not time to show off.

SLIP · Post by **SLIP** » 20 Mar 2006, 14:50

AlphA · Post by **AlphA** » 20 Mar 2006, 14:51

-=WiK1d=- wrote:You should try to keep it balanced...

2 in 2 out...
15 in 15 out...

But I find the best way for me is having 1x120mm blowing from the back of the case and 1x120mm extracting in the front...

Wikid --> Are you aware that hot air rises? The idea is to suck cool air at the front of your case, it will then get warmed up on the inside of your case and then rise. Once it has reason, the extractor fan (which should be at the back) should blow it out the case.

Oj · Post by Oj » 20 Mar 2006, 17:30

Thanks for your replies! I'll try all blowing out tomorrow. Oh yeah, on the topic of blowing out, check this out

http://www.casemodgod.com/Howto-story--42.html

WiK1d · Post by **WiK1d** » 20 Mar 2006, 17:36

AlphA wrote: Wikid --> Are you aware that hot air rises? The idea is to suck cool air at the front of your case, it will then get warmed up on the inside of your case and then rise. Once it has reason, the extractor fan (which should be at the back) should blow it out the case.

Actually..I know hot air rises...i've had my fans like front in back out...then I changed it around and my CPU temp dropped with 3-5*C...that is why i said it...but ya...in theory it won't work bla bla bla same old speech...

AlphA · Post by **AlphA** » 20 Mar 2006, 17:38

Its amazing that it worked for you that way! Are both fans rotating at the same speed?

Well, whatever works for you

WiK1d · Post by **WiK1d** » 20 Mar 2006, 17:41

Yep...both are antec tricools at full speed...

AlphA · Post by **AlphA** » 20 Mar 2006, 17:45

Strange - like I said.....if it works for you.....

I need to re-fit my Hardcano 13 again tomorrow (it was faulty and was replaced).......I'll try your method and see what differences it makes in my system...

Asbestos · Post by **Asbestos** » 20 Mar 2006, 22:21

Oj.
From personal experience I can tell you that having all your fans blowing outwards does keep the case cooler, until there is so much dust and grit covering your pc internals that they overheat anyway and your motherboard fans sieze up completely.

Always, always, have a positive case pressure, it keeps the dust out better. You'll thank me if you ever clean out a case that has been running for 3 years with all fans blowing out. :crazy:

Bobendren · Post by **Bobendren** » 20 Mar 2006, 23:41

You say you will have 5 fans, i take it this includes the PSU fan?

I reckon 3 out and 2 in. This will give the case a slight negative pressure, which is better for temps. Seal up anywhere air can enter the case, except for the fan intakes obviously. Buy some dust filters to cover the intake fans.

Actually no intake fans are required if you seal up properly and cover the openings you do want with dust filters. Intake fans are only really necessary for people running hot gfx cards and multiple hard drives. If you aren't in this boat then all the front intake fan is doing is reducing the pressure on the exhaust fans which isn't important provided there is enough area for air to enter. Maybe an undevolted 80mm fan to cool a hdd but that's all.