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Push vs. Pull Tested

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a c 110 ) Power supply
May 19, 2012 1:11:47 AM

*NOTE* THIS IS A SCIENCE PROJECT I NEED YOU GUYS TO HELP ME EVALUATE IT!! :D  (Please post the scores that you think I deserve with this Rubric: https://docs.google.com/viewer?a=v&pid=sites&srcid=Y3Vz... )
(Currently transferring project, photos etc. over to forum post from google docs.)

PC Cooling: Push vs. Pull, Which Performs Better?


Abstract
I tested the performance differences between Push (Fan is pushing air through the heatsink) and Pull (Fan is pulling air through the heatsink). In order to get temperature results I ran stress tests 3 times and got the averages of each fan setup. I found out a fan pushing air through a heatsink will provide better cooling, than a fan pulling air. Not only can this be the deciding factor between heatsink A or heatsink B, this can be very helpful to first time users wondering where they should mount their fans.

Introduction
In every modern day computer, there is a fan and heatsink to take heat away from the processor. A heatsink is designed to absorb the heat generated from the processor and a fan is used to dissipate the absorbed heat from the heatsink by pulling/pushing the heat away. Without a heatsink, processors would burn out by overheating.

How a Heatsink Works


1) Processor generates heat.
2) Heatsink absorbs generated heat via heatpipes/plating.
3) Heat is brought up to heatsink fins (hot air rises).
4) Fan brings cool air across the heated fins, causing them to become cooler.
5) Absorbed heat in fins are dissipated.
6) Cool air molecules absorb the heated air molecules.
7) Heated air molecules are removed from the case via exhaust.

Materials and Testing Methodology
The system was ran in both overclocked and stock configurations for minimum and maximum temperature readings. Ambient temperature* in the room was a cool 20.5C which did not change between each fan configuration. The processor was overclocked from a stock of 3.3ghz to a speedy 4.5ghz and the voltage was raised from 1.1v to 1.34v. The fan used in this experiment was an Aerocool Shark 120mm Fan, which pulls around 85.5CFM (Cubic Feet Per Minute). The Shark was ran at a max speed of 1600RPM (Revolutions Per Minute) for consistent results and maximum performance.The fan was then mounted in both Push and Pull configurations on the heatsink and temperatures were taken with CPUID’s Hardware Monitor.

To stress the processor and take temperatures, I used the following programs:
Stress Testing**
10 Minute Prime95 Run (Used to check for a stable overclock by stressing processor)
http://www.mersenne.org/freesoft/
10 Passes of Intel Burn In Test (Maximum stress testing for all cores)
http://downloads.guru3d.com/IntelBurnTest-v2.3-download...
*NOTE* None of these will simulate real world temperatures, these are just used to indicate which fan configuration works BEST for YOU.
Temperature Reading
Hardware Monitor
http://www.cpuid.com/softwares/hwmonitor.html
*Ambient temperature is the “temperature of your surroundings” essentially, room temperature
**In order to generate consistent results, each test was ran 3 times and the average temperature was taken.

Test Hardware
CPU: Intel Core i7-2600k @4.5ghz 1.34v
Motherboard: Asrock Z68 Extreme 4 Gen 3
RAM: 16GB Patriot Sector 7 DDR3
Heatsink: Cooler Master Hyper 212 EVO/Aerocool Shark 120mm
Thermal Paste: Arctic Silver 5
Case: CM 690 II Advanced
Power Supply: Antec HCG 620W Power Supply
Graphics Card: Nvidia Geforce GTX 550ti

Aerocool is a reputable company when it comes to fans, their shark series of fans performs very well and is able to generate consistent results when mounted on the Cooler Master Hyper 212 EVO.

Aerocool Shark 120mm Fan Compared to Other Fans


Fan mounted on heatsink:

Thermal Paste applied:

Cooler Installed:








Fan Differentiations
Push



Pull



Notice how the fan on the heatsink in the “Pull” photo is flipped? This is what denotes the difference between the Push and Pull methods!




Test System Fan Setup

Fan Setup: 140mm Intake 2x 120mm Outtake 1x 140mm Outtake 2x 120mm Intake

Results
*these for some reason don't work, so click on them for results*
http://img526.imageshack.us/img526/8673/intelburnin.jpg
http://img443.imageshack.us/img443/5541/prime95c.jpg



Performance Differences:
Push offers 2C-4C difference in performance when compared to Pull. This is on average a 2.8-5.6% difference between the two. Even though the temperature difference doesn’t seem like a lot, it can be crucial to users who want the best possible temperatures.

As the data shows, when a fan pulls hot air from a heatsink, it will perform better than a heatsink pushing the air. Keep in mind these temperatures will never be reached during real world applications and uses such as gaming and common tasks like internet browsing. However, temperatures will be different between both fan setups regardless of the task being given. Remember, temperatures may be different for everybody, this is because ambient temperature is different in many parts of the world.

Discussion
As shown, temperatures between Push and Pull methods do not vary much! As said before, these do not simulate real world performance. They only show which fan configuration is best and works for you. You may ask yourself, why would someone want to use the Pull method when the Push method works better? Well, there are some cases where RAM Modules get in the way of the fan and block the fan from being installed. That is the only reason why one would use the Pull method instead of the Push method.


Acknowledgments

I would like to thank 4Ryan6 of Tomshardware.com for allowing me to use his CFM and airflow results of the Aerocool Shark 120mm fan. I would also like to thank Tomshardware.com and Cooler Master for the photos on airflow. The original Tomshardware.com article on PC Aircooling: http://www.tomshardware.com/reviews/cooling-airflow-hea... Without Tomshardware.com Forums, I would not have been able to come up with the idea for this project! I would also like to thank FinneousPJ and many other people for helping me with ideas and evaluating this project.

More about : push pull tested

a b ) Power supply
May 19, 2012 1:43:35 AM

hooray muffin
Your photos don't work, though.
a c 110 ) Power supply
May 19, 2012 3:22:47 AM

Because I haven't added them :o 
Related resources
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a c 104 ) Power supply
May 19, 2012 5:04:33 AM

Cool project man, however this series of experiments only shows that xx fan performed better in xx setup on xx heatsink
for a truer indication of the old 'which is best' you would have to repeat the entire set with different fans and heatsinks,
Seems like a perfect opportunity to grab some freebies from Companies in the name of 'research'
Hehe, I like it man and look forward to your further adventures
Moto
a c 110 ) Power supply
May 19, 2012 5:16:19 AM

I don't know how to grab freebies though, plus I don't think any companies would send fans to a kid like me :( 
a c 104 ) Power supply
May 19, 2012 6:02:59 AM

Lay out your brief, include some data like you already have, and Email it to fan/heatsink companies saying you intend to evaluate say 20 popular fans on the top 5/10 heatsinks and would they be interested in participating?
at least a couple of guys on here get stuff for reviews and evaluation purposes,
as well as the modders who get sponsor offers,
age is irrelevant, if you present the plan in a well thought out fashion and show your professional intentions, you may be surprised at the replies you get
Moto
a b ) Power supply
May 19, 2012 12:53:39 PM

Yep. Watch your formatting. Making a professional first impression is important. I'd be happy to check your initial letter over if you like.
May 19, 2012 1:56:59 PM

I want pictures :D  ! pretty well done experiment I was wondering how "big" will be the difference between push/pull fans configurations...

I have a Hyper212 with its stock cooler in push configuration, I wanted to try how good or bad would be if I install a small and fast fan pulling air from the front (just under the DVD drive) blowing air through rams and directly to the heatsink, and move the Stock Fan in the pull configuration taken the air just to the back... Still I haven't enough time, I guess that I will be doing that this weekend !

Keep it up, it would be great if you get some kind of help and check fans/heatsink configuration for our knowing ;D !
a b ) Power supply
May 19, 2012 2:05:00 PM

Are you looking for comments before you present this at school or did you just want to post the results?
a b ) Power supply
May 19, 2012 3:21:56 PM

you will get even better temps if you use pull but block the sides of the heatsync so your pulling air all the way through the fins rather than getting high pressure at the edges and low in the middle. at least in theory it should be more efficient.

May 19, 2012 3:37:22 PM

horaciopz said:
I want pictures :D  ! pretty well done experiment I was wondering how "big" will be the difference between push/pull fans configurations...

I have a Hyper212 with its stock cooler in push configuration, I wanted to try how good or bad would be if I install a small and fast fan pulling air from the front (just under the DVD drive) blowing air through rams and directly to the heatsink, and move the Stock Fan in the pull configuration taken the air just to the back... Still I haven't enough time, I guess that I will be doing that this weekend !

Keep it up, it would be great if you get some kind of help and check fans/heatsink configuration for our knowing ;D !


Push/Pull did very little for me but 1-1.5 C.....I have a 120 exhaust 4" from the back of the Heatsink

Waiting for pics
a c 110 ) Power supply
May 19, 2012 6:09:04 PM

I want some comments before I give my teacher the project on monday! If you guys can evaluate me too.....that would be awesome! I'll fix up the photos soon ok?
a b ) Power supply
May 19, 2012 6:24:46 PM

Look forward to seeing the pics and graphs.

Am curious about hexits thoughts on blocking the sides, i tried this with push and blocked sides were warmer, but I was surprised by the result. I also wanted to test a plenum chamber between the fan and the fins to get rid of the dead zone in the middle.

Definitely ask for samples, it might be the start of something interesting (I imagine it's how toms originally started back in the day), at the very least it'll be interesting and a differentiator when it comes to CV time.
May 20, 2012 4:34:05 AM

ok in your starting you forgot to include if that was 1 16GB DDR3 stick or 2x8GB or 4x4GB to get a total of 16GB of DDR3 you also forget the speeds in MHz and CAS latency as these also factor into it
you forget to include what kind of cooling that was used on the Graphcis Card which i suggest against as using the intergrated graphics processor will give off less heat inside of the case then any cooler on any decaited graphics Card
links to all the parts should be included and sited in your list of sources at the bottom of your report
the liquid colling system and the liquid used was not listed and you should also list its the chemical makeup of it and compare how it changes if at all when the temperatures raise and fall
i did nto see a spot in which the results were posted if they are posted make it more clear where they are
the Pull seciton was blank please fix that before turning it in
Like the people above adding in pictures will add interest into your project
a c 110 ) Power supply
May 20, 2012 5:08:28 AM

RAM Sticks, Speeds don't matter.
Cooling on the graphics card does not matter.

As for photos and actual editing, I am working on that now...
a c 110 ) Power supply
May 20, 2012 5:45:21 AM

Motopsychojdn said:
Lay out your brief, include some data like you already have, and Email it to fan/heatsink companies saying you intend to evaluate say 20 popular fans on the top 5/10 heatsinks and would they be interested in participating?
at least a couple of guys on here get stuff for reviews and evaluation purposes,
as well as the modders who get sponsor offers,
age is irrelevant, if you present the plan in a well thought out fashion and show your professional intentions, you may be surprised at the replies you get
Moto

Going to email some companies. Which ones should I email? I need a suggestion list...BTW can some of you guys help me write one?

List:
GELID
Noctua
Phobya
Cooler Master
Antec
Scythe

BTW Where do I find each companies email :( 
a b ) Power supply
May 20, 2012 9:33:29 AM

This is a high school project right? I think you should get a B.

Some things you could add/change:

A bit more in-depth look into a heatsink. How does it actually work, why is there a fan. To really impress your teacher, look up some basic concepts of thermal physics and how they relate to this engineering problem.

It would have been cool if instead of revealing your results in the first chapter you had some discussion as to what you think is going to happen and why. Then you present the results, and again it would be great if you had some analysis as to why and what is going on.

Use less exclamation!!! :p 

With these changes it would pass a university course I'm sure, good job anyway.
a b ) Power supply
May 20, 2012 10:14:31 AM

Your pull image has the heatsink rotated, but the fan is still pushing through the heasink, you need to turn the fan round on the image too.
a b ) Power supply
May 20, 2012 10:19:52 AM

Oh yeah, what you claim is Pull is actually Push - and what you claim is Push is pushing in the wrong direction. Flip the fan to achieve Pull.
a c 110 ) Power supply
May 20, 2012 11:07:58 PM

Are you sure? I thought Pull was the fan in the front of the heatsink pulling air (intake) But push was on the back? :/ 
a c 110 ) Power supply
May 20, 2012 11:08:28 PM

FinneousPJ said:
This is a high school project right? I think you should get a B.

Some things you could add/change:

A bit more in-depth look into a heatsink. How does it actually work, why is there a fan. To really impress your teacher, look up some basic concepts of thermal physics and how they relate to this engineering problem.

It would have been cool if instead of revealing your results in the first chapter you had some discussion as to what you think is going to happen and why. Then you present the results, and again it would be great if you had some analysis as to why and what is going on.

Use less exclamation!!! :p 

With these changes it would pass a university course I'm sure, good job anyway.

Middle school project! :sweat:  Alright, I need to add those things.
a c 76 ) Power supply
May 20, 2012 11:17:56 PM

amuffin said:
Are you sure? I thought Pull was the fan in the front of the heatsink pulling air (intake) But push was on the back? :/ 


You got confused there. Yeah, the fan is taking in cool air, but it's also "pushing" cool air through the fins. Pull would be the other way, pulling cool air through the fins.
a c 110 ) Power supply
May 20, 2012 11:45:06 PM

Changing stuff now...
a b ) Power supply
May 21, 2012 7:37:54 AM

the pull is definitely wrong, (I can't tell if you are still editing). The fan direction on the pull model should from the heat sink to the case. On push the fan should be from the case to the heat sink.

Also your model of 'how a heat sink works' is missing some key elements, the 'fan dissipated generated heat' for instance is not really telling the story, 'fan generates air flow', 'heat is transferred from fins to air', the heat rises element is not important, as thats only airflow, in fact in 90% of PC cases it rises away from the heatsink. Perhaps putting the transfer mechanism on each element would be useful, convection, conduction etc.
a c 110 ) Power supply
May 24, 2012 10:42:57 PM

did some moar editing.
a b ) Power supply
May 25, 2012 9:36:58 AM

Here, I made a picture of Pull to demonstrate:



See how the fan is pulling the air through the heatsink instead of pushing?

You might want to add citations to some bits where you reference other people's material like Tom's and stuff.
May 25, 2012 11:22:04 AM

Cool air does not come out of heatsink sir warm air does.
a b ) Power supply
May 25, 2012 11:29:01 AM

Well that depends on how effectively the heat sink is cooling. Stick a huge cooler on top of a low power Sandy Bridge Pentium and I assure you there will be cool air coming from the heat sink no matter what the load. You could say ideally there is cool air coming from the heat sink.
May 25, 2012 11:56:08 AM

FinneousPJ said:
Well that depends on how effectively the heat sink is cooling. Stick a huge cooler on top of a low power Sandy Bridge Pentium and I assure you there will be cool air coming from the heat sink no matter what the load. You could say ideally there is cool air coming from the heat sink.


No it does not you are simply not thinking this through.
a b ) Power supply
May 25, 2012 12:09:09 PM

If your computer is not blowing cool air at idle your cooling configuration is insufficient. I have "thought it through" - even tested it: when I had a custom water cooling loop it blew cool air even at full load, overclocked - the maximum CPU temperature was 27 centigrade.
a b ) Power supply
May 25, 2012 12:14:46 PM

It would blow ambient + idle wattage power transferred to the ambient air. Which at idle should be only 15-20W, which would equate to only a 2-3C above ambient as air output temp. Not warm, but not cooler than ambient which is where spentshells is going.

the heat energy taken up by the heatsink will be the same regardless of the heatsink, it'll be of a lower 'grade' i.e. more dispersed and lower temp with a bigger capacity heatsink (heatsinks should in my opinion be rated according to watts able to be dispersed at standard airflows and delta T's) . I say bigger and not better as the quality judgement in better may not work out if you had a heatsink the size of a case for instance for instance it would be massively oversized and therefore probably not better for the job at hand.
a b ) Power supply
May 25, 2012 12:33:48 PM

Nobody said cooler than ambient lol, that would impossible :/ 
a b ) Power supply
May 25, 2012 12:35:12 PM

Its the definition of 'cool air' though, spent was being picky I think, your meaning and your words were a little at odds.
a b ) Power supply
May 25, 2012 12:57:23 PM

13thmonkey said:
Its the definition of 'cool air' though, spent was being picky I think, your meaning and your words were a little at odds.

In which dictionary? So the ambient air can't be "cool" by your definition? :lol: 

Cool is defined by Merriam-Webster as lacking in warmth - that seems rather subjective. When I put my hand behind my CPU cooler at idle the flow of air feels cool, as in sufficiently below body temperature.
May 25, 2012 2:26:16 PM

FinneousPJ said:
If your computer is not blowing cool air at idle your cooling configuration is insufficient. I have "thought it through" - even tested it: when I had a custom water cooling loop it blew cool air even at full load, overclocked - the maximum CPU temperature was 27 centigrade.


if the air being pushed out was cool why would it need to be pushed out in the first place ? Why push away cool air when you are trying to cool something ?
Come on guy think about it a little harder


More on this Muffin I am pretty sure the heatsink dissipates (as per moto) the heat not the fan. The fan pushes away the heat dissipated by the heatsink
a b ) Power supply
May 25, 2012 2:27:23 PM

Don't patronize me, I know what I'm talking about.
May 25, 2012 3:07:15 PM

FinneousPJ said:
Don't patronize me, I know what I'm talking about.



It does not seem that way at all. If the air is cool why is it being pushed away ? Because it is not cool it is warm.
a c 104 ) Power supply
May 25, 2012 3:10:48 PM

@Finneous, I wasn't patronising you man, you hadn't specifically said air cooling and claimed lower than ambient was impossible, I responded on that basis,
sorry if offence was caused, it wasn't intended
Moto
a b ) Power supply
May 25, 2012 3:12:20 PM

Motopsychojdn said:
@Finneous, I wasn't patronising you man, you hadn't specifically said air cooling and claimed lower than ambient was impossible, I responded on that basis,
sorry if offence was caused, it wasn't intended
Moto

No, not you, the guy with the mask :D 
May 25, 2012 3:19:20 PM

FinneousPJ said:
No, not you, the guy with the mask :D 



Hey I see what you are trying to say after reading other peoples comments.


MUFFIN as for your images the top one should not show cool air coming out as the air is being warmed by passing over the heatsink and exhausted from the case because it is warm not cool right ?
a b ) Power supply
May 25, 2012 3:28:42 PM

It seems there's some sort of miscommunication going on here. I'll try and elaborate my points the best I can.

a) there's no chance the air coming out of a heatsink is cooler than ambient. By cool I mean if the heatsink is doing it its job if you put your hand in there it should feel cool.

b) The function of the heatsink is not to blow warm air out. The function of the heatsink is to pull air from the CPU by means of heat pipe technology in this case, then dissipate the heat through cooling fins. If the air coming out the heatsink is hot, that actually means it's not dissipating the heat fast enough. Obviously that's not a problem as long as the heat plateaus at a reasonable level.
a c 110 ) Power supply
May 25, 2012 5:50:10 PM

FinneousPJ said:
Here, I made a picture of Pull to demonstrate:

http://img109.imageshack.us/img109/2310/pullv.png

See how the fan is pulling the air through the heatsink instead of pushing?

You might want to add citations to some bits where you reference other people's material like Tom's and stuff.

I'll be borrowing that.... :love: 
a c 110 ) Power supply
May 25, 2012 5:51:22 PM

spentshells said:
Hey I see what you are trying to say after reading other peoples comments.


MUFFIN as for your images the top one should not show cool air coming out as the air is being warmed by passing over the heatsink and exhausted from the case because it is warm not cool right ?

Wouldn't be considered "cooler" air? Right? Correct me if I am wrong here....
May 25, 2012 6:31:21 PM

amuffin said:

Performance Differences:
Push offers 2C-4C difference in performance when compared to Pull. This is on average a 2.8-5.6% difference between the two. Even though the temperature difference doesn’t seem like a lot, it can be crucial to users who want the best possible temperatures.

As the data shows, when a fan pulls hot air from a heatsink, it will perform better than a heatsink pushing the air. Keep in mind these temperatures will never be reached during real world applications and uses such as gaming and common tasks like internet browsing. However, temperatures will be different between both fan setups regardless of the task being given. Remember, temperatures may be different for everybody, this is because ambient temperature is different in many parts of the world.

I have underlined where there is an error. This statement should be reversed. You say later on that Push is more effective than Pull. You should also add a second mention of the word "fan" in the second part of that sentence, so it doesn't sound like the heatsink is what is pushing the air.

This goes beyond the original scope of your experiment, but I would like to see what difference there is between mounting the heatsink vertically (like you have it now) versus horizontally, with a heatsink model that uses heatpipes. I have heard that the "wicking" effect that the heatpipes use is reduced by gravity when you have them mounted vertically, which is why I have mine mounted horizontally.
May 25, 2012 6:38:35 PM

FinneousPJ said:
It seems there's some sort of miscommunication going on here. I'll try and elaborate my points the best I can.

a) there's no chance the air coming out of a heatsink is cooler than ambient. By cool I mean if the heatsink is doing it its job if you put your hand in there it should feel cool.

b) The function of the heatsink is not to blow warm air out. The function of the heatsink is to pull air from the CPU by means of heat pipe technology in this case, then dissipate the heat through cooling fins. If the air coming out the heatsink is hot, that actually means it's not dissipating the heat fast enough. Obviously that's not a problem as long as the heat plateaus at a reasonable level.


B is wrong I am sorry if I was coming off as rude earlier but you are not being helpful since this is a science project.

The fan blow the heat off of the heat sync this the air coming off of it is warmer than it was upon intake *truth
May 25, 2012 6:48:30 PM

amuffin said:
Wouldn't be considered "cooler" air? Right? Correct me if I am wrong here....



Exactly warmer air is coming off the back of the heatsink else where is the heat going ?
!