H60 - Push/Pull with different fans?

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Dayle McNeela

Dayle McNeela

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Hi All!

I will be using the Corsair H60 to cool my CPU... (i5 3570K) and I plan to be overclocking to 4.0 - 4.5GHz...

I want to know, if I use a push/pull config on my radiator (exhausting into my case, drawing cool air from ambient) but use 2 fans with different CFM ratings, what will happen performance wise?

This will be the config;

Rear of Case > Scythe Ultra Kaze (133CFM) > H60 Rad > Corsair SP120 (38CFM) >Interior of Case

So the high airflow fan will be pushing cold air from my rad, and the low CFM fan will be pulling the hot air into my case...

I will have 2 x Scythe Glide Stream 140mm Case Fans (106CFM) above this config (on the top panel of case) to exhaust all the hot air...

I was thinking, if there is a low cfm fan pulling the air into the case, then the exhaust fans above should be able to catch the hot air better?

I am using the Corsair 350D windowed version case.

EDIT: I Will be using a 6 Channel Fan Controller and I have 2 x Front Intake (Scythe Ultra Kaze 120mm 3000rpm 133CFM), 2 x Exhaust (Scythe Glide Stream 140mm 1600rpm 106CFM) and the 2 x Intake around my rad as discussed above)

Total Intake - 437CFM
Total Exhaust - 212CFM
 
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Azrael47
the fan corrugation that I suggested and the one that is portrayed in the diagram is the best for you. Get two fans that are good for small clearance and make sure they operate at the same RPM.
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Azrael47

Azrael47

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In your last thread I explained that it would best for you to do a pull/pull configuration IF you have a top outlet fan. Those fans will be fine for the H60, however the fans that come with the H60 are the SP120's which are recommended/specifically designed to be used for radiators /heatsinks. You are exactly right with the exhasut fans.

Make sure you have an intake.

 
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Dayle McNeela

Dayle McNeela

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Hello again, did some research on pull/pull and from what I can see, there is no such thing?
I have attached a picture of what I plan to do..

Push-Pull-config.png


The Fan that 'Pushes' will be the 133CFM and the fan that pulls will be the 38CFM
 
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Azrael47

Azrael47

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I apologise I have been misleading I always thought that it was called Pull/pull. The diagram above is a exactly the method I recommend. I think you can understand why I thought it was pull/pull as both fans (in theory) are pulling/sucking cool are into the system. This will be your best fan configuration for the H60 I assure you!




I recommend that you watch this>https://www.youtube.com/watch?v=UyC3lZ5WFMk
 
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Dayle McNeela

Dayle McNeela

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I understand, push/pull makes no sense when you think about it but here we are.
What i really need to know, if Ive i have a powerful, fast fan pushing air through a slow moving fan, will this damage the slow fan or is it best to match the fans?
 
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Azrael47

Azrael47

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not at all, why will you have a fast fan and a slow fan, would they not just operate at the normal RPM.


The reason why this fan configuration is best for your CPU is because cool air will be sucked from outside of the case, the second fan will also help with the speed of the air hitting the radiator which will make temperatures slightly better. The hot air from the case will be sucked out BY the top outlet fan.

Personally I would want the fans to co-exist and run at the same RPM as one another.

 
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C12Friedman

C12Friedman

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Azrael meant Push/Pull (likely a typo) in his response. Although I am not a purist when it comes to matching fans, with the big differences in airflow volume between those two fans, I foresee problems such as overspeeding on the lower volume fan (will make it wear faster). If you are determined to do that combo, I might suggest using the 38CFM fan as push (easier to push than pull) to reduce strain upon it - still not liking it, why not run two ultra-kaze's (or is that too wide?)
 
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Liam Joyce

Liam Joyce

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yeah just think about it ..lol do you really want two different cfms acting against eachother... the fast one will be trying to speed up the slow one and the slow one will either be operating to fast or bring down the performance of the fast one ? .. at least that seems what would happen ... just buy 2 of the same fan save urself the guess work
 
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Dayle McNeela

Dayle McNeela

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Azrael got confused with the config types.
I thought having 2 different fans would be a problem, think i will just get 2 Ultra Kaze's...
That would make 101mm (10.1cm) not sure if this is too big?
 
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Dayle McNeela

Dayle McNeela

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I think ill try a push config first, see how that works out, then try the push/pull config (push/pull will equate to 10.1cm long... not sure if this will create problems...)
 
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Dayle McNeela

Dayle McNeela

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2 x Corsair Air Series SP120s?
63CFM...
 
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D

dingustaargus

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Everyone is so smart but you are all thinking ahead of yourselves..
Everyone is SO quick to assume that the same fan would be better without actually using logic when taking a lot into consideration.

Fans made for static pressure only perform better when something is in front of them....

So the SP fan would be good to use for PUSHING the air into the Radiator.

The AF fan would be better at pulling.

Using the same fans in both push and pull would cause the pull fan to out perform the push fan no matter what fans you use because there is nothing blocking the airflow of the pull fan, it will obviously blow a higher cfm..

Also take into consideration that even an SP fan will be hindered by having a radiator in front of it.

So the real answer to this mystery can be found using a very common problem solver we like to call math.

You have to take a lot into consideration.

The SP fan will be better as the push fan because it will allow for better airflow

The airflow fan will be better for the pull fan because there will be nothing blocking its airflow and will be able to perform how it is meant to.

Whichever fan you use will have its CFM drop the higher density of the Radiator/Heatsink. Which means you want to use a higher RPM fan as the push and the LOWER RPM fan as PULL.

Some math must be done to figure out the curve.

Example:

Your SP fan is pushing 40cfm through your radiator at 1500 rpm. If the SP wasnt pushing through the radiator at 1500rpm and had nothing blocking its airflow, it would achieve a higher CFM (lets say 60cfm).

Take your AF fan and find out at what speed it will get the same CFM (40cfm) without blockage. Chances are the af fan will only have to run at about 1300 RPM to achieve 40 CFM. So that would mean a fan that runs at 1300rpm and pushes 40cfm without blockage should be your choice for pull.

An SP fan that pushes 40CFM at 1500 rpm can be your second choice.

So the Pull fan does NOT need to be optimized for pressure.

It does NOT make sense to use pressure fans as PULLERS.

It does not make sense to use the SAME fans for push/pull (unless you lower the RPM of the PULL) because the pushers performance will be hindered due to the radiator blocking it. which will turn your matching RPM/CFM Fans into unmatching fans..

You want to match your CFM of your unblocked pull fan to the CFM of your blocked PUSH fan.

Think before you write things people.. And don't be so quick to assume things without thinking them through.

Figure out your CFM Curve and match your CFM. Do not match your fans unless you can use a fan controller to turn the RPM of the pull fans down a bit to match.

I will say it one more time in case anyone couldn't understand my rant.


The RPM of the fan doesn't matter. what matters is what CFM you get in what circumstance.

If you use the same fan at the same RPM you will not achieve the same CFM with both push and pull fans.

The PUSH will have the lower CFM.

This is bad.

It is much better to mix and match fans or lower the speed of your pull fan to match the CFM of your push.

You may be able to accomplish this using sound as a reference, but this will be hard for anyone who has little experience with fans.

Cheers EVERYONE! And I hope I made you all think about this a little differently. ;)
 
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C12Friedman

C12Friedman

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Rather than explain the errors within this, I'll simply refer you to something we call "Fluid Dynamics" which explains the principles involved in airflow and the math (with real formulas and everything).
 
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R

Richard LaMountain II

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It does make sense one set of fans is grabbing air from the (outside or inside, depending on exhaust or intake choice) and pushing it through the radiator. The other set is pulling the air through the radiator. Is aspect to the where the fans are mounted on the radiator not the fan orientation themselves.

 
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Liam Joyce

Liam Joyce

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so .... should I be angry at antec for supplying me 2 of the same fan with my antec kuhler 920 ? refund? lol
 
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