push or pull?

Soldato
Joined
28 Jan 2011
Posts
8,535
hey guys,

ordering my new cooler soon, it will be a 120mm rad and fan, what is the best combo for this? push or pull? or two fans? or what?



RTJ
 
Push/pull is normally about 20-30% better than just one or the other. I believe the order of best to worse is normally:

Push+pull
Push
Pull

(although there is little difference between the last two so if it suits your situation to go with one or the other then I wouldn't be worried)
 
For push/pull to be 20-30% better the fans used would not be much good or there is extreme resistance in the cooler. In most applications the difference is minimal to maybe 3c. How fans perform in push or pull depends on the fans involved. Some push better, some pull better.
 
For push/pull to be 20-30% better the fans used would not be much good or there is extreme resistance in the cooler. In most applications the difference is minimal to maybe 3c. How fans perform in push or pull depends on the fans involved. Some push better, some pull better.

This, push pull was kind of a thing that came to be when we didnt have the kind of quality static pressure fans we have now. This video will tell you all you need to know to make a decision:

 
"didnt have the kind of quality static pressure fans we have now" is before my time, and I'm older than dirt. Gentle Typhoon fans are almost as old as I am. :D

Sorry, but Linus often makes the village idiot look like a genius. His identity ten tea errors are legendary, as is your video link. In case you don't know that means, try ID-10-T and remove the dashes.
The resistance is not just a middle kind of thing. Stacking fans increases their abilbity to overcome resistance, so if you have a very low resistance fan on a cooler, putting another one on other side will help. But don't try putting one fan on another. There needs to be a 'airflow straightener' between them .. this tops the circular flow a spinning fan creates so 2nd fan can work properly.

And his 'always run radiators in pull' is for people too stupid to simply and/or too lazy put filters on all intakes and clean the filters as needed. Running a system for a year is just plain identity ten tea.

You could always stack the fans like this. :D
https://youtu.be/VUbpb23yTK8?t=581
 
Haha that link is class Doyll rofl. Linus is a right tool and I just can't listen to the babble that comes out of his mouth. Whoever pays him the most is what he recommends.
 
Stacking fans increases their abilbity to overcome resistance
So long as their performance figures are not too opposing...
You want either two fans the exact same, or if you have to, a slower fan pushing into a faster pulling fan - Doing it the other way around causes a compression stall and typically ends up breaking the push fan.

However, it also depends on the fin spacing of the heatsink and how your fan(s) of choice work with that. If the fin space is too narrow and the airflow spread too wide, the air will bounce around inside the heatsink, slowing down and again causing a compression stall. A similar thing happens if the fan SP is not high enough to blast enough air through the heatsink.

And his 'always run radiators in pull' is for people too stupid to simply and/or too lazy put filters on all intakes and clean the filters as needed.
Or those who are more interested in using the darn thing instead of shifting the workstation about, disassembling everything, carrying a big heavy case downstairs and outside, just to dust it out every week...
 
So long as their performance figures are not too opposing...
You want either two fans the exact same, or if you have to, a slower fan pushing into a faster pulling fan - Doing it the other way around causes a compression stall and typically ends up breaking the push fan.

However, it also depends on the fin spacing of the heatsink and how your fan(s) of choice work with that. If the fin space is too narrow and the airflow spread too wide, the air will bounce around inside the heatsink, slowing down and again causing a compression stall. A similar thing happens if the fan SP is not high enough to blast enough air through the heatsink.


Or those who are more interested in using the darn thing instead of shifting the workstation about, disassembling everything, carrying a big heavy case downstairs and outside, just to dust it out every week...
Stacking 2x of the same fans works very well at increasing their ability to overcome resistance. While this doe not increase their airflow capability when there is no resistance, it does increase their ablity to overcome resistance significantly. If one fan has a airflow resistance stall level (static pressure) of 3.0mm H20 and our working resistance is 2.0mm we have imaginal airflow even with fan at full speed. if we have two if these fans stacked with a straightener between them 2.0mm of resistance is futile. They will blow it away without blinking an eye.

Exactly why I use filters. Take them off of case and hoover the dust off. I don't even need to move my case, just pull the filter out from under it for bottom and open front to access front filter.

This is also why there are few cases I will use .. because very few cases are built by people who have a lick of common sense about maintenance. Things like PSU filters on bottom that pull out the back of case. :mad: Why not at least make them so they can be pulled out of either side? Or better yet, do like Fractal Design did on the R5 and the whole bottom is a filter that slides out the front.
 
if we have two if these fans stacked with a straightener between them 2.0mm of resistance is futile.
It varies, depending on the combination of the heatsink and the spread of the airflow, as to how well the straightener will actually straighten.

Exactly why I use filters. Take them off of case and hoover the dust off. I don't even need to move my case, just pull the filter out from under it for bottom and open front to access front filter.
I found filters actually restricted the airflow enough to make a noticable difference, as well as reducing but not eliminating dust, so the case still needs taking outside...

This is also why there are few cases I will use .. because very few cases are built by people who have a lick of common sense about maintenance.
Or more likely built by people who are catering to consumer budgets... There is a lot that could be done to make cases better, but I certainly wouldn't be able to afford it!

Or better yet, do like Fractal Design did on the R5 and the whole bottom is a filter that slides out the front.
My case sits sideways, partly so the window faces forward and partly so I can reach the cables at the back. Side or forward filter removal is not an option for me.
 
It varies, depending on the combination of the heatsink and the spread of the airflow, as to how well the straightener will actually straighten.
Stacked fans either need a straightener or one running in reverse rotation to other.

I found filters actually restricted the airflow enough to make a noticable difference, as well as reducing but not eliminating dust, so the case still needs taking outside...
Sure filters restrict airflow about as much as grills do. I would rather not have grills than not use filterers on intakes. I get very little dust buildup in my systems, so little I do a through clean less than once a year more like every 18 months to 2 years.

Or more likely built by people who are catering to consumer budgets... There is a lot that could be done to make cases better, but I certainly wouldn't be able to afford it!
It's a lack of common sense. There is no more expense in making a case with easy access to filter than the way they are now. The basic airflow design of case is 10-20 years old. Best airflow in a tower is front to back .. not lower front & bottom to upper back & top. Middle top and front top venting is counter productive to smooth case airflow.

My case sits sideways, partly so the window faces forward and partly so I can reach the cables at the back. Side or forward filter removal is not an option for me.
If it works for you that's all that matters.
 
Back
Top Bottom