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View Full Version : Which direction does AMD and INTEL fans move air



nedkelly
20-05-2009, 04:44 PM
Hey I am wondering if any one knows what direction AMD and INTEL fans move air

wratterus
20-05-2009, 04:45 PM
You're talking about CPU fans? All standard fans push air toward the back of the fan, eg down onto the CPU.

nedkelly
20-05-2009, 04:47 PM
i was told that one sucks air on to the cpu cooler and the other sucks air through the cooler then up and off the cpu cooler

CYaBro
20-05-2009, 04:47 PM
Hey I am wondering if any one knows what direction AMD and INTEL fans move air

Usually pull air down through the fan and out through the heatsink.
You see some cases that have a tunnel from the side cover over the CPU fan so that it can pull cool air from outside the case.

nedkelly
20-05-2009, 04:50 PM
so do they both suck the same way?

CYaBro
20-05-2009, 04:52 PM
so do they both suck the same way?

Yup, just double-checked a couple of AMDs in the workshop and they are sucking down through the fan onto the heatsink.

pctek
20-05-2009, 04:56 PM
one sucks air on to the cpu cooler and the other sucks air through the cooler

Other what? There is only one fan on a CPU - whether or not its Intel or AMD. And they all push air onto the heatsink, always have.

Erayd
20-05-2009, 05:14 PM
Other what? There is only one fan on a CPU - whether or not its Intel or AMD. And they all push air onto the heatsink, always have.

Except some of the HP / Dell ones, which have some extremely strange configurations - particularly in their SFF cases.

1024KB
20-05-2009, 05:18 PM
That one's pretty straight forward, you need the constant flow of force-fed air onto the heat sink to prevent instant burn-out.

Where the manufacturers do have it cocked-up is the case fans though. Every case with a single extraction fan is doing it the wrong way round. Extracting air means the case has slightly less air pressure than the surrounding environment. Less air pressure means less cooling air available (this is NOT ideal). Also, when you switch off, the last action is sucking air into the case (via all other inlets) - hence the monstrous internal dust build-up (a la vacuum cleaner), even in spotless homes.

The oh-so-simple remedy is to simply flip your case fan over, reversing the air flow - so it blows cool air into the case. 4 screws out, flip, 4 screws back in, done.

Fresh air being forced in = better cooling, and slightly more air pressure than the surrounding environment means the final action is puffing air out of the box - no more dust bunnies!

Try it, it's one of the simplest improvements you can make to your desktop box.

Erayd
20-05-2009, 07:01 PM
The oh-so-simple remedy is to simply flip your case fan over, reversing the air flow - so it blows cool air into the case. 4 screws out, flip, 4 screws back in, done.That is a very stupid idea - you'll mess up the internal airflow of the case, and it'll generally run hotter. By all means add an intake fan at the front, but flipping the rear fan is a bad idea.

If your power supply has an exhaust fan (and almost all of them do) then your 'remedy' is even worse, because it just shuttles cool air round in a circle between the rear fan and the PSU fan, and does almost no real cooling work.


...means the final action is puffing air out of the box - no more dust bunnies!Rubbish. You'll still get just as much dust in the case, no matter which way round you flip the fan - you're still shifting the same volume of dust-laden air through the interior of your computer system.

Sweep
20-05-2009, 08:38 PM
so do they both suck the same way?

If you are only talking about a CPU fan both will suck air out of the case and push it on to the heat sink in order to cool the CPU.

Do you mean that the fans (CPU) revolve clockwise or anticlockwise to achieve the same result.

All fans (for CPU )to me revolve clockwise which unless you put it in upside down would mean that the fan would blow rather than suck.

What, really, is your question?

Most vacuum cleaners have fans in them. You can use use some vacuum cleaners with the right attachments to spray paint for example. If the fan was sucking I guess you might get a load of paint inside the cleaner. If the fan was blowing you may get the desired result or not.

To check this wave your hand over the PSU unit outside the case. Can you feel warm air coming out? So if you can it is blowing air out of the case and cooling the PSU. Therefore it will be sucking on the inside but from where you are it will be blowing.

We have been though this issue before.

tweak'e
20-05-2009, 10:42 PM
Hey I am wondering if any one knows what direction AMD and INTEL fans move air
both blow air on the cpu heatsink. however there are a few odd heatsinks that are specially designed to work the other way around.



The oh-so-simple remedy is to simply flip your case fan over, reversing the air flow - so it blows cool air into the case. 4 screws out, flip, 4 screws back in, done.
very bad idea. that will suck in all the hot air from the other rear fans (such as psu) and will cook the pc.
what you really need to do is fit a front case fan that flows more than all the rear fans. the downside to that is it increases the noise.
tho that won't help a lot with dust build up except it tends to blow out what it blows in.
if your seeing dust build up aroudn the edges of the case it measn the inlet isn't big enough.

1024KB
21-05-2009, 12:09 AM
Alrite then, grab yourself a copy of SpeedFan (www.almico.com/speedfan.php). Run it. Then flip yer fan & run SpeedFan again.

(I did this long ago when testing this method out. It aint newbie waffle. It works.)

Cook your PC? Oh dear.

Sweep
21-05-2009, 01:35 AM
both blow air on the cpu heatsink. however there are a few odd heatsinks that are specially designed to work the other way around.


very bad idea. that will suck in all the hot air from the other rear fans (such as psu) and will cook the pc.
what you really need to do is fit a front case fan that flows more than all the rear fans. the downside to that is it increases the noise.
tho that won't help a lot with dust build up except it tends to blow out what it blows in.
if your seeing dust build up aroudn the edges of the case it measn the inlet isn't big enough.

Hmmmm.....

I have not yet seen AMD or Intel fans in a case other than over the CPU.
Some people I note have the case on the floor so the front fan can suck the air through the case along with all carpet fibres and dust mites etc.

Some people have a case on the desk with a side fan which can also blow greeblies into the case.

Before anyone says there house is 100% free of unwanted dust I suggest they look out the window at or near dawn or dusk. You may see particles floating or not in the room you are in.

Erayd
21-05-2009, 03:10 AM
I did this long ago when testing this method out. It aint newbie waffle. It works....
Then your testing method sucks. Simple logic will tell you that it doesn't work.

1024KB
21-05-2009, 06:35 AM
Here's some simple experiments for you - to go with your simple logic.

Wet your hand (to amplify the feeling & negate the warmth of your breath) now hold it in front of your mouth. Blow on it - exhale. Now the reverse, inhale.

Which one makes your hand feel cooler?

Got a reversible vacuum cleaner? Give that a go. Which airflow direction makes your hand cooler? Blowing or sucking?

When you burn your finger - do you blow cool air onto it? Or suck warm air away from it?

Or, let's take it up in scale & swap appendages for electronics, hence bringing it back to the original argument. Take the side off your desktop box. What would you rather use to cool the insides with, a fan or a vacuum cleaner?

In summer, does your car's air conditioning blow cold air into the cabin? Or have you reversed the fan to suck all the hot air out instead? (You might be onto something here! Don't give up your day job yet though.)

How's your simple logic going?

Actually, I do remember one case manufacturer that provided a rear intake fan rather than exhaust - Lian Li.

JJJJJ
21-05-2009, 07:27 AM
Hmmmm.....

I have not yet seen AMD or Intel fans in a case other than over the CPU.
Some people I note have the case on the floor so the front fan can suck the air through the case along with all carpet fibres and dust mites etc.

Some people have a case on the desk with a side fan which can also blow greeblies into the case.

Before anyone says there house is 100% free of unwanted dust I suggest they look out the window at or near dawn or dusk. You may see particles floating or not in the room you are in.

My case has a 100mm fan in front that sucks cold air in and another at the back that sucks hot air out.
Only problem . my ash tray sits right in front of the front fan. The smoke rises verticaly and when it reaches the fan it turns 90* straight into the case.
I've often wondered what it would do to cooling if I reversed the fans and sucked fresh air in the back and out the front

pctek
21-05-2009, 08:22 AM
my ash tray sits right in front of the front fan.
I've often wondered what it would do to cooling if I reversed the fans and sucked fresh air in the back and out the front

Blow ash all over your desk.

But it would still cool - its airflow - so long as you reversed both, and you have good cable management.

Although the PSU does the same thing too you know.

Erayd
21-05-2009, 02:03 PM
Here's some simple experiments for you - to go with your simple logic.

Wet your hand (to amplify the feeling & negate the warmth of your breath) now hold it in front of your mouth. Blow on it - exhale. Now the reverse, inhale.

Which one makes your hand feel cooler?

Got a reversible vacuum cleaner? Give that a go. Which airflow direction makes your hand cooler? Blowing or sucking?

When you burn your finger - do you blow cool air onto it? Or suck warm air away from it?

Or, let's take it up in scale & swap appendages for electronics, hence bringing it back to the original argument. Take the side off your desktop box. What would you rather use to cool the insides with, a fan or a vacuum cleaner?

In summer, does your car's air conditioning blow cold air into the cabin? Or have you reversed the fan to suck all the hot air out instead? (You might be onto something here! Don't give up your day job yet though.)

How's your simple logic going?

Actually, I do remember one case manufacturer that provided a rear intake fan rather than exhaust - Lian Li.

You really don't understand the principles involved here, do you. Go find yourself a physics textbook. Find the section dealing with energy, specifically heat transfer. Read it.You might also want to consider the fact that your blow / suck experiments are badly flawed - if you want to prove something, you need to design your experiment in such a way that any external influences are identical for each step (or removed entirely, but that isn't always possible).

Gobe1
21-05-2009, 02:56 PM
Agreed Eryad, he doesnt understand physics

Paul.Cov
21-05-2009, 04:11 PM
Actually, our Megabyte friend makes a lot of sense, and I have long questioned the industry standard methods of cooling.

He is correct with his explanation of the positive pressure case being better for achieving heat transfer from the heat sink and CPU to the air, although the advantage is very small.

It is also correct that a positive pressure case (with air intake part way up the wall of the case) will collect less dust inside. Gravity results in most dust ultimately settling on the floor, or the desk. Basically whatever surface the computer sits on will also be a place that gathers dust. A negatively pressured case will suck in air through all gaps, and the gaps near the floor/desk will have more dustto offer up to the inside of the computer, in addition to all the airborne dust.
A positive pressure case will only pick up airborne dust. Dust from floors will be greater than dust from desks.

Having a CPU fan scattering hot air all over the rest of the inside of the computer is stupid. It essentially turns all the components and the case itself into a radiator of heat.
Ideally, the CPU fan should be moving air straight from the heat sink to the exterior of the case. This would keep the entire system running cooler.

Our current systems are just a hangover from the days when all that was needed was a single exhaust fan in the PSU (not even a CPU fan), and the design has not been properly overhauled since.

tweak'e
21-05-2009, 04:19 PM
My case has a 100mm fan in front that sucks cold air in and another at the back that sucks hot air out.
Only problem . my ash tray sits right in front of the front fan. The smoke rises verticaly and when it reaches the fan it turns 90* straight into the case.
I've often wondered what it would do to cooling if I reversed the fans and sucked fresh air in the back and out the front

if you reversed the rear and front case fan the case temp would go up.
this is because your forgetting about the PSU fan.

PSU fan blows hot air out which will simply get sucked in the rear fan. that air in the case will simply get blown out by the PSU fan again, around around in circels.
the front fan will pull a little bit of air thorugh the case but over all you will have dropped the amount of air flow and the air that does come in will be hot air.
obviuosly how much air depends on case fan sizes and how they fight/work with each other.

easiest way is move the ash tray.
have you seen what smoke does to a pc? its amazing some last as long as they do.

with back would fans i used to see a fair few of them becasue the PSU had overheated and died.
if they didn't have a rear fan, just blocking up the fan location used to drop the case temps.

1024KB- heat sinks have to be designed specially for reversed fan setups. one of the good old ons was the alpha heat sink. in its day it was huge with wide fine spacing and a suck fan arrangement.
but higher heat and the need for close fins to get big surface area means suck fan arrangement won't work. lots of thin close fins require a bit of force to get air to move between all the fins, hence the use of high speed fans in blow arrangement. swap the fan over and you will just get a partitial vaccum, no air MASS going past the fins hence not much cooling.

tweak'e
21-05-2009, 04:41 PM
Having a CPU fan scattering hot air all over the rest of the inside of the computer is stupid. It essentially turns all the components and the case itself into a radiator of heat.
Ideally, the CPU fan should be moving air straight from the heat sink to the exterior of the case. This would keep the entire system running cooler.


not by much at all. exhaust air temp off the cpu heatsink is not a big amount due to the decent amount of air flow through it. plus its also mixed with more case temp air then sucked out shortly after. its not really being blown around the case. the few extra degrees it can make to other componants is nothing that they can't handle. (eg ram and power regualtors).