Which is more important? A stronger intake or exhaust fan?

[LuDaCriS66]

Which is more important to have a cooler case environment?? A stronger CFM rated intake fan or exhaust fan? I ask this because the 80mm fan that was included with my Antec SX630 seems awfully weak as an exhaust. I have a 36CFM Sunon fan for the intake.

The thing is, I will be adding a dust filter on my intake fan soon... somewhat restricting the airflow. I guess I should just buy a new 80mm fan to replace the Antec case fan?? The damn thing feels like it's 20cfm or something. It's very weak.

How good are the 80mm panalfo fans?? Whats the difference between the High and Low ratings on the Panalfo fans? Are they representing the noise level or the air flow?

BTW, my temps are fairly decent. If the room is cool, then my case temps are usually around 25-28 degrees celsius and my CPU temp hovers around 38-42. I'm using an SK6 with a 5000rpm YS-Tech fan

 

[Sabbathian]

Hell-o !

By my experience, both intake and exhaust are important. I have two 80mm
Titan coolers for intake, and two 80mm titan coolers for exhaust, and they work perfectly !

 

[Sorgon2]

This is correct. You wanna try to create a balance of flow thru the case if possible. Quite a few cases and mod cases out there have 2 intakes and 2 outakes. Panaflos are a good choice for case fans. Quiet and very efficient. The difference between H and L is the amount of power the fan provides. There is also a Medium Panaflo. You will notice a difference between the H and L versions in regards to noise, but IMHO the H output Panaflos are not necessarily ear piercing. Good Luck!

 

[phlashphire]

Exhaust is more important. mainly because of it's location, right next to the hottest component of the computer- the cpu. I know someone can definitely explain this better. If I had to choose between 2 fans for intake or exhaust, I'd definitely take the exhaust.

 

[Sabbathian]

Well, I can`t agree with you, becouse, if you have, for instance 2 exhaust vents,
and only one intake, you are pumping out the hot air, but whith what are you replacing it with ?
You need cool air to replace the hot one that went out !

 

[ubersam]

<< if you have, for instance 2 exhaust vents, and only one intake, you are pumping out the hot air, but whith what are you replacing it with? You need cool air to replace the hot one that went out ! >>


You'd still be replacing the outgoing air [hot] with outside air [cool]. But since what's being blown in isn't as much [in volume] as what's being sucked out, air will sucked into the case from other openings. The case isn't airtight.

 

[boyRacer]

The Lite-On FS020 works on negative pressure... and it seems to work very effectively. But it does use 120mm fans so im sure thats more than enough air needed. Two 120mm in the back and 1 in front. If u were going to get Panaflos get U1As...

 

[THUGSROOK]

actually im using all exaust fans.

front, back, blowhole, and 2 PSU fans exaust.
i have 2 120mm holes in my side panel for 2 120mm intake fans, but the exaust fans suck so much air thru those 2 openings that i dont even need to install fans there. i did install grilles tho

i know this against the norm, but it works great, isnt as loud, and its not as dusty

 

[MoFunk]

I am using 3 exhaust and 1 intake.
Intake is a 92mm with blowhole in the front. Then I have an 80mm exhaust right next to my CPU, my enermax PSU works as exhaust with 2 fans, a 92mm and an 80mm. Then at the very top of my tower I have another 92mm exhaust. Been working great. I am soon going to replace the front 92 with a 120 though.

 

[DongTran]

IMO more important to blow hot air out. this creates a vacuum and cold air would come in anyway. sucking air in w/o blowing it out just mixes it....maybe you could create your own tornado by mixing in the hot and cold air?

 

[DongTran]

hmm, re: the tornado idea, i'm not quite sure how you would create an internal updraft in your system, and plus you need like rain and hail and stuff to make the tornado touchdown, otherwise it'd be just a funnel. HMMMM, interesting cooling idea HMMMMMM. maybe if we could somehow make an internal funnelling swirling affect, that would be the best way to channel heat away from from whatever since the velocity of funnels is much faster than regular airflow, kind of like what that company e-ram was doing to cars a while back. whatever i'm babbling bored @ work maybe i'll do some work now okay thank you bye

 

[trikster2]

According to AMD the exhaust is more important.

Source:

AMD guide to cooling etc


?¡Use an auxiliary exhaust rear chassis fan. The suggested size
is 80 millimeters or larger. The fan intake should be near the
location of the processor.

?¡For best results, use an ATX power supply with air intake
venting in the processor region, which means that the pri-mary
air intake is on the bottom of the power supply, not at
the front of the power supply. Supplies with NLX-style vent-ing
(the primary air intake is at the front of the power sup-ply)
do not pull air from the processor area.

?¡A front cooling fan is not essential. In some extreme situa-tions,
testing showed that these fans recirculate hot air
rather than introducing cool air.

 

[RalfHutter]

Obviously no one in this thread subscribes to the "positive pressure equals less dust in your case" theory. Any thoughts on this senario?

 

[THUGSROOK]

RalfHutter-

i personally think that negitive pressure keeps the dust out

 

[RalfHutter]

The theory is that negative pressure pulls air (and whatever resides in it - i.e. dust) into the case through whatever openings it can find. This includes the innards of your floppy drive, optical drives, HDD's etc. The way the theory goes is that if you have positive pressure you won't get so much dust build-up inside your case. I'm not a "positive pressure" die-hard by any means but I lean that way. It's how I set up my cases but I've never done any kind of scientific testing.

 

[dnoyeb]

Intake is more important

A high pressure zone will absorb more heat than a low pressure zone. Its just like a turbo in a car. If the air in your case is more dense, then it can move more heat.
So if you have more exhause flow, you will have low pressure which will not absorb as much heat as if you have more intake fans since the intake fans will create
a high pressure zone.

Now you need to get the air out too. But if your air is moving and you want to add an extra fan, make it an intake.

 

[DongTran]

<< Intake is more important

A high pressure zone will absorb more heat than a low pressure zone. Its just like a turbo in a car. If the air in your case is more dense, then it can move more heat.
So if you have more exhause flow, you will have low pressure which will not absorb as much heat as if you have more intake fans since the intake fans will create
a high pressure zone.

Now you need to get the air out too. But if your air is moving and you want to add an extra fan, make it an intake. >>



whoa whoa whoa, I'm thinking hold the phone. Wow, I've never seen anyone justify the analogy of a CPU and turbocharged car. Turbocharged cars produce MASSIVE heat, there's a reason we have intercoolers for them. Now if you had some kind of moisture-free refridgeration/air-conditioning unit for your front fan, then that's a different story.

If you check out most dells or whatever, you'll see that a lot of them have channels that go around the socket, then straight out to the back with a fan pushing air out. They're assuming that you don't live in the Sahara and the ambient temp is almost always cooler on the outside than on the inside...

Anyway it's a common law of physics. So you are telling me a pressure cooker will freeze my food? In MOST situations depending on CPU plasement, case layout, etc..., a vacuum will always benefit your system more. Get rid of that hot air!!!!

 

[element2k5]

personally i think ur gonna get dust with moving air regardless, but the fans should always be balanced... a fan is only as good as the slow one

 

[dnoyeb]

<<
whoa whoa whoa, I'm thinking hold the phone. Wow, I've never seen anyone justify the analogy of a CPU and turbocharged car. Turbocharged cars produce MASSIVE heat, there's a reason we have intercoolers for them. Now if you had some kind of moisture-free refridgeration/air-conditioning unit for your front fan, then that's a different story.

Anyway it's a common law of physics. So you are telling me a pressure cooker will freeze my food? In MOST situations depending on CPU plasement, case layout, etc..., a vacuum will always benefit your system more. Get rid of that hot air!!!! >>



A vacuum has no air, thus will provide no cooling...

Lots of talking but little logic. A turbo produces compressed air. That was my point. A pressure cooker cooks fast because water boils at a higher temperature under pressure. Again, this is not a direct analogy.

My logic stands. Dense air can hold more energy. Take your CPU and FAN combo into outer space and see how long it lasts...

You can move more air by either moving more molecules per blow, or blowing more often.

How is a nuclear power plant cooled? Compressed water. Rather, "heavy" water. Same principle.

 

[DongTran]

<< A vacuum has no air, thus will provide no cooling...

Lots of talking but little logic. A turbo produces compressed air. That was my point. A pressure cooker cooks fast because water boils at a higher temperature under pressure. Again, this is not a direct analogy.

My logic stands. Dense air can hold more energy. Take your CPU and FAN combo into outer space and see how long it lasts...

You can move more air by either moving more molecules per blow, or blowing more often.

How is a nuclear power plant cooled? Compressed water. Rather, "heavy" water. Same principle. >>



In nuclear power plants, they have multimillion dollar water coolers

When you have a vacuum inside your computer, there are more molecules of air on the outside than the inside. By the law of diffusion, air will naturally flow in through the front grills or whatever grills you have on your computer. Our consumer computers are never airtight, and almost always have an intake and exhaust pattern.

Could you apply your standing logic to the dense air in the core of the earth? Take your CPU and FAN combo into air pocket (if you can find one) in the core and see how long it lasts...while on the subject of density, taking our CPU and FAN combos into space has nothing to do this discussion - we're talking about moving air from one medium to another using fans.

Air travels at higher velocities at lower pressures. I will use the Venturi Principle to demonstrate this, which I am sure almost all of you are aware of. To refresh the memory of those of you who have forgotten, the Venturi Principle is a narrow constriction in a pipe of some sort that creates a partial vacuum immediately after the constriction. The vacuum created the lowers the pressure of the liquid or gas passing through it and increases the velocity because the vacuum creates a sucking effect.

One example, real-world example, I'm not saying that Dell computers are the best, but they are the best selling. I'm pretty sure that their cooling techniques work, and that they have to work well if they sell millions of the same model of PCs. We have 600 Dell Optiplex GX150 towers here where I work, every single one of them have a single fan that is mounted on the CPU and blows outward.
dell schematic

Another example, Enermax power supplies. Sure two fans are better than one, but on the power supplies that they have that use only one fan - for example the EG301P-VB that come in Enermax cases has a fan blowing out. Why is this? The fan blowing out creates a vacuum that sucks air in via the front grills of the power supply.
enermax EG301P-VB

If any of this information is incorrect, please by all means post your rebuttle....

 

[bigbuffmelonhead]

<<

<< A vacuum has no air, thus will provide no cooling...

Lots of talking but little logic. A turbo produces compressed air. That was my point. A pressure cooker cooks fast because water boils at a higher temperature under pressure. Again, this is not a direct analogy.

My logic stands. Dense air can hold more energy. Take your CPU and FAN combo into outer space and see how long it lasts...

You can move more air by either moving more molecules per blow, or blowing more often.

How is a nuclear power plant cooled? Compressed water. Rather, "heavy" water. Same principle. >>



In nuclear power plants, they have multimillion dollar water coolers

When you have a vacuum inside your computer, there are more molecules of air on the outside than the inside. By the law of diffusion, air will naturally flow in through the front grills or whatever grills you have on your computer. Our consumer computers are never airtight, and almost always have an intake and exhaust pattern.

Could you apply your standing logic to the dense air in the core of the earth? Take your CPU and FAN combo into air pocket (if you can find one) in the core and see how long it lasts...while on the subject of density, taking our CPU and FAN combos into space has nothing to do this discussion - we're talking about moving air from one medium to another using fans.

Air travels at higher velocities at lower pressures. I will use the Venturi Principle to demonstrate this, which I am sure almost all of you are aware of. To refresh the memory of those of you who have forgotten, the Venturi Principle is a narrow constriction in a pipe of some sort that creates a partial vacuum immediately after the constriction. The vacuum created the lowers the pressure of the liquid or gas passing through it and increases the velocity because the vacuum creates a sucking effect.

One example, real-world example, I'm not saying that Dell computers are the best, but they are the best selling. I'm pretty sure that their cooling techniques work, and that they have to work well if they sell millions of the same model of PCs. We have 600 Dell Optiplex GX150 towers here where I work, every single one of them have a single fan that is mounted on the CPU and blows outward.
dell schematic

Another example, Enermax power supplies. Sure two fans are better than one, but on the power supplies that they have that use only one fan - for example the EG301P-VB that come in Enermax cases has a fan blowing out. Why is this? The fan blowing out creates a vacuum that sucks air in via the front grills of the power supply.
enermax EG301P-VB

If any of this information is correct, please by all means post your rebuttle.... >>



I agree DONGTRAN, I have the exact power supply that you mentioned above. I believe Enermax do make some of the best power supplies out there. The intake/exhaust pattern is indeed very valid. In short, I believe that is "vacuum" effect that DONGTRAN states is most likely the most efficient way to cool your computer. SO! GO EXHAUST!

 

[dnoyeb]

Its just not that simple. First of all the ATX has specifications on how the fans are supplosed to blow. ATX power fan is supposed to blow in...

Sure you will not ALWAYS have better performance blowing in. It depends on how the air moves away. Its not a simple case. Its a complex case of thermodynamics and differential equations.
I am making a general statement though.

Your statement of milliion dollar water coolers on nuclear power plants seems to dance around the logic of why I made the nuclear plant example in the first place.

I can't answer your core of the earth arguement because I don't understand your point, being that the core is very hot. But if you mean pressure wise, then yes.

If you take your computer into a high pressure chamber, its cooling capabilities will increase. If you take that same computer into a low pressure chamber, its cooling capabilities will decrease. This is the physics I am basing my arguement on.

In retrospect I think we are both wrong and right. If the air in the case was already dense (high pressure chamber), it would improve cooling. However, the air is not getting denser until it passes through the CPU fan. Taking from your arguement, the number of molecules passing by is not increased, nor decreased by the increased pressure due to the CPU fan since the air speed is reduced.
Therefore, blowing causing high pressure on the processor is NOT contributing to the cooling. However, as far as case fans are concerned, you do wan't increased pressure and air density.
So the processor fan should simply face in the direction you test to be better. The case fans should blow more in than out so as not to create a vacuum in the case, but create a highpressure zone with more dense air.

All based on the fact that dense air is capable of transporting more heat.
And I think I should add a caveat. This increased pressure should not come at the cost of volume of air flow. At equal volumes of air flow however, the pressurized case beats the vacuumed case. So given an equal number and CFM fams, 1/2 shoudl blow in, 1/2 should blow out. But with an odd number, put the extra one blowing in.




You can significantly improve the cooling abilities by using a humidifier. Of course then you have to worry about corossion

 

[Mikewarrior2]

<< Its just not that simple. First of all the ATX has specifications on how the fans are supplosed to blow. ATX power fan is supposed to blow in... >>



Actually, ATX 2.0 and UP in spec have the atx power supply fan blowing out....



Mike

 

[dnoyeb]

<<

<< Its just not that simple. First of all the ATX has specifications on how the fans are supplosed to blow. ATX power fan is supposed to blow in... >>



Actually, ATX 2.0 and UP in spec have the atx power supply fan blowing out....
Mike >>



Oh well...I just looked at the spec yesterday and noted that the AT days had air blowing out, but the ATX had air blowing in. Maybe I missed an ammendment.
Makes since since in these days if high power when the PSU could be blowing its own hot air. But if you add 2 more fans, I would put them both blowing in.

 

[Mikewarrior2]

It goes beyond that... with the ATX 2.0 and UP spec compliance forcing Power Supply fans to exhaust air (and this makes sense, you don't want a 400W power supply and its hot compenents blowing its warm air into the case).

remember that the AMD cooling spec states that fans should be set to exhaust and should also be near the CPU...

AT the very least, you want to maintain some kind of balance balance between exhaust and intake... if you're gonna only have one fan, make it an exhaust fan near the CPU. Per AMD cooling instructions (and since AMD chips run the hottest out of the current chips, that has to say something for AMD's case cooling recommendations[/b]), there should at least be an exhaust fan.

If you're gonna have more fans, i'd go and try to balance them out.


Mike