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more intake or more exhaust?

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clocker2

Member
Joined
Dec 5, 2003
Location
Mile High
Hard to tell.
Does you're machine run cooler with the sidepanel off?
Is the top of your case warmer than the bottom/middle?
Where is your intake located?
The exhaust?
How many/what size fans do you have?

Inquiring minds want to know.
 

bafbrian

Member
Joined
Jan 30, 2003
Location
Atlanta, GA
Honestly, you need more intake than exhaust. You want postive airflow in your case. This means less dust and a cooler computer.

More exhaust means more dust and a hotter computer.
 

itizme

Member
Joined
Nov 3, 2002
Location
Barrie
Your case however should have some way of exhausting other than the power supply. Try to leave one fan port open to allow the pressure to attempt to balance. Keeping more incoming is the idea though.
 

Korndog

Member
Joined
Nov 30, 2002
Location
California
Most computer manufac. like dell, compaq, and HP have more exhaust then intake, sometimes no intake at all. they do this for a reason... a computer case isn't air tight, it has air leaks from just about every where so how can you make sure air is getting to your cool air is getting to your cpu? The air from the intake will only know where to go if its guilded by the exhaust fans, otherwise who knows where its going.
IMO, more exhaust :)
 

stool

Senior Member
Joined
Dec 20, 2000
Location
Albany, NY
My own opinion, but what you really should have is as close a balance between intake and exhaust as you can get. NEVER base your cooling on what the majors do, because cooling is not one of their priorities.
Too much exhaust, and you'll end up drawing in air in places you don't expect(like through your floppy and/or CDROM), with the dust that goes along with it.
 

clocker2

Member
Joined
Dec 5, 2003
Location
Mile High
Obviously, there is more than one way to skin a cat.
I think the only way to find your best solution is to try out every combination you can think of.
Pick some sort of benchmark to run for consistent test conditions and then record the results.
I probably tried at least 20 different configurations before I settled on a fan layout that I really liked.

Now I've switched to water cooling and get to start all over.:eek:
 

daemoslives

Registered
Joined
Oct 20, 2003
Location
Padded walls, straightjacket, sound familiar?
If you have more intake than exhaust, your intake fans will burn out quicker. This may not be a problem in the short run, given the rate people replace computers nowadays. But I think its best to have an even CFM balance between intake and exhaust, maybe a few CFM more on the intake. Dust shouldnt really be a problem if you have filters in place in front of your fans.
 

rogerdugans

Linux challenged Senior, not that it stops me...
Joined
Dec 28, 2001
Location
Corner of No and Where
Stool and clocker2 made my points. :)

There are some generalizations that are used in cooling that usually hold true...but NOT always!

The most accurate:
Intake low in front, exhaust high in back.
This allows cool air to flow in low and has the natural pattern of heat rising help exhaust the hot air- all without recycling case air.
Even this is not guaranteed to be right however- some have switched things completely around and gotten better results.

There are two different schools of thought regarding the amount of intake and exhaust in a case:
"Positive pressure" - more intake than exhaust. Thought to keep dust out and supply more components with cooler air by many
"Negative pressure"- more exhaust than intake. Though to keep hot air exiting as fast as possible and allow cool air to get in to hard to vent areas.

(Note- Positive and negative pressures do not truly exist in our cases- the terms are just used to indicate relative amounts of flow.)

One thing agreed on by most- and even here NOT all!- is that having airflow close to balanced will provide best results for either scheme.

Personally, I have found having slightly more exhaust to be better most of the time and I have very little problem with dirty components.

And this brings me to Experimentation.
The only way to determine what really is best in your system is to experiment because these general rules can and do have exceptions.
I have an example-
I built an air-cooled, slightly oced system that needed to be QUIET.
I used a good heatsink with 7volted fan, 7volted the psu exhaust and added 1 case 120 mm intake and 1 80mm exhaust, both 7 volted. Just about silent with temps just a bit high- 46c or so @ 100% load.
I removed the intake fan and temps dropped to 42c or so full load. No active intake at all, although a 120mm opening (with fan grill) in front for passive intake.

For best results rely on nobody but yourself- Experiment!
 

mccoyn

Senior Member
Joined
Nov 17, 2003
Location
Michigan, USA
One thing not to do is have all exhaust. My Dell at work only has exhaust and everytime we open it it is packed with dust.
 
OP
Pollux

Pollux

Member
Joined
Nov 29, 2003
its an antec sonata, i bought a 2nd fan for it: an enermax 120mm adjustable. i currently have it as intake, and the stock fan as exhaust. my temps are 39-41 idle and 44-46 load.
 

clocker2

Member
Joined
Dec 5, 2003
Location
Mile High
It seems to me that you have a couple of decisions to make.

First, where would you like your temps to be and how far are you willing to go in the pursuit?
Second, if you make a radical mod (in terms of permanence, that is- like cutting a new fan hole...) can you live with the results should it fail to work as hoped?
Third, if the answer to #2 is yes, are you willing to spend the time to see it through? When you start to cut holes you are pretty much going to be stripping your case bare for every attempt. Cut, move fan, reassemble, benchmark, evaluate...rinse and repeat.
This can really eat up time, not to mention be rather frustrating- for every idea that works there are 9 that don't.
Chances are, you'll actually succeed in making thing worse before they get better.

It ain't easy, but it is fun and you'll learn a lot should you persevere.
 

chkptcharlie

Member
Joined
Dec 2, 2003
Location
Olive Branch, Mississippi
^^^ what he said ^^^

My case has 1 intake fan and 2 exhaust fans at the moment. however i have several rows of small holes in my case in an attempt to balance out the equation. this may not be the best way, but at the moment it cools enough for me.

Dont forget doing this kinda stuff is also a chance to get creative... if you have a cool idea that might work, and are willing to carry it out, try it. who knows you might actually suprise yourself on what you can find.
 
OP
Pollux

Pollux

Member
Joined
Nov 29, 2003
im not going to cut that beautiful case :( . right now i have more intake than exhaust, since my intake fan is more powerful, should i leave it like that, or switch the fans?
 

blkgti

Member
Joined
Aug 5, 2003
Pollux said:
right now i have more intake than exhaust, since my intake fan is more powerful, should i leave it like that, or switch the fans?

As you're the one with the case and the fans, why don't you try them both ways and see which works for you best.
 

Sir Barton

Member
Joined
Mar 22, 2003
Location
Fort Pontchartrain du Détroit
ive experimented on mine recently, and ive found that having more exhaust than intake works better for me. i only have 2 80mm fans, but the rear is an SF2, and the front is an enermax adjustable 80mm. i have the SF2 running at 3700rpm and the enermax at 2500rpm. with positive pressure, i was getting 42C idle, w/ negative pressure i im getting 36C idle. having more exhaust made a big difference for me.
 

xace

Member
Joined
Mar 30, 2003
Location
Daytona, FL
clocker2 said:
Hard to tell.
Does you're machine run cooler with the sidepanel off?
Is the top of your case warmer than the bottom/middle?
Where is your intake located?
The exhaust?
How many/what size fans do you have?

Inquiring minds want to know.

I agree with clockers way of finding out. find the weakness in your case and chose the best solution.