Push-Pull Question.

[Twilight_Poplar]

When fans run in series, such as in a Push-Pull configuration, and the fans have different CFM is the total CFM the average of both (or however many you have in the series) fans?

 

[Conumdrum]

It isn't push+pull equals output. There is a heatsink in the middle. So it matters not as a number, but a general mathmatical increase, better cooling, more air passing over the cooler.

That said a higher CFM is best on the push side.

 

[Twilight_Poplar]

However, that being said, if two fans are in series with no heatsink would the slower fan somehow bottleneck the faster one?

 

[Conumdrum]

YES.

It's just how physics works.

 

[bburrill2012]

That said a higher CFM is best on the push side.

Not always the case. Some cpu coolers maybe not have a great deal of CFM's but end up being cooler than other cpu coolers because of the design of the heatsink/fan setup. Some heatsinks and fans are made in such a way they do not need high cfm. Static air pressure from the fan and how the heatsink is made to need the static air pressure to keep it cool.

I have an Xigmatek Aegir and with the fan it comes with which is rated at 61 (says like 90 or something but that is a typo) cools my cpu great. I took that fan off and used a scythe ultra kraze 133 cfm fan on the heatsink and under load temps only dropped 1C.

 

[bburrill2012]

However, that being said, if two fans are in series with no heatsink would the slower fan somehow bottleneck the faster one?

You would think so, but not always the case again

I took an XAF-F1255 and the Scythe Ultra Kraze. 90cfm and 133cfm fans.

I used them both in a push-pull setup on my Aegir. Swapped them to see if there was any difference. None. Under full load with Prime95 the temps were within 1C of eachother with the two fans in a push-pull and swapped for comparison.

 

[bluezero5]

in parallel = same static pressure , add the CFM

in series = same CFM, add the static pressure.

if series, if one fan stronger. Strong CFM fan wins, it will start to 'float' the lower fan in some cases. Easy way to test this theory, is turn off one fan, and keep the other fan on. Now you have 1 fan with no CFM and 1 fan turning the other.

 

[bluezero5]

You would think so, but not always the case again

I took an XAF-F1255 and the Scythe Ultra Kraze. 90cfm and 133cfm fans.

I used them both in a push-pull setup on my Aegir. Swapped them to see if there was any difference. None. Under full load with Prime95 the temps were within 1C of eachother with the two fans in a push-pull and swapped for comparison.

that only means your radiator is good enough to radiate all the heat required. On a more bottlenecking system. (say 800 W of heat disspating through a 240 radiator), you will see significant difference.

but of course, you should never always use enough radiators. and in those situation, the difference will likely be small.

 

[bburrill2012]

Not talking about on my radiator, i dont have liquid cooling. I am talking about on my Xigmatek Aegir heatsink for my cpu.

 

[bluezero5]

Not talking about on my radiator, i dont have liquid cooling. I am talking about on my Xigmatek Aegir heatsink for my cpu.

you know that silver thing right in the middle of your air cooler?
that is a radiator. ... just in case you didn't know.

now reread what I wrote.
if you OC your CPU any further, the fan will matter.

but of course, not suggesting that you should, if you are happy with the performance, then great.

 

[bburrill2012]

you know that silver thing right in the middle of your air cooler?
that is a radiator. ... just in case you didn't know.

now reread what I wrote.
if you OC your CPU any further, the fan will matter.

but of course, not suggesting that you should, if you are happy with the performance, then great.

Actually a radiator has some kind of liquid that runs through it, so therefore its a heatsink to be exact, even tho it may act as a radiator or serve the same purpose as one.

And ive taken my cpu to 4.8-5.0ghz and it still didnt matter. The other fan didn't help much at all. I just wouldnt want to have to super load hovercraft sound to have it 1-2C cooler on the core temps. Not worth it IMO

 

[TheHutchTTU]

Actually a radiator has some kind of liquid that runs through it, so therefore its a heatsink to be exact, even tho it may act as a radiator or serve the same purpose as one.

And ive taken my cpu to 4.8-5.0ghz and it still didnt matter. The other fan didn't help much at all. I just wouldnt want to have to super load hovercraft sound to have it 1-2C cooler on the core temps. Not worth it IMO

A radiator is a heat exchanger, regardless of medium.

By the way, air = fluid

 

[Steven90]

A radiator is a heat exchanger, regardless of medium.

By the way, air = fluid

Dang, beat me to it!

 

[bburrill2012]

A radiator is a heat exchanger, regardless of medium.

By the way, air = fluid

Straight from the dictionary

1.
a person or thing that radiates.

2.
any of various heating devices, as a series or coil of pipes through which steam or hot water passes.

3.
a device constructed from thin-walled tubes and metal fins, used for cooling circulating water, as in an automobile engine.

 

[TheHutchTTU]

Straight from the dictionary

1.
a person or thing that radiates.

2.
any of various heating devices, as a series or coil of pipes through which steam or hot water passes.

3.
a device constructed from thin-walled tubes and metal fins, used for cooling circulating water, as in an automobile engine.

I don't disagree with with this statement, but now let's look at definition 1 and define radiate.

The emission of energy.

If you have taken any physics class you would know that heat is a form of energy.

That thing on top of your CPU is radiating heat to the heatpipes and ultimately out to the fins, where the heat is dissipated through convection.

Therefore, by definition, it is a radiator.

 

[bburrill2012]

Anyway, from my experience just because a fan produces more cfm doesnt mean it will cool any better.

 

[manu2b]

Straight from the dictionary

1.
a person or thing that radiates.

That's me!

 

[manu2b]

Well, guys, don't play with words like this, ok?

In this world, a radiator is the stuff we use for WC, otherwise we say "heatsink".

And don't start with "Yes, but the meaning of words...blah blah blah..." please, ok?

Do you want the new member to leave the forum already?

Is he not "elite" enough for you?

 

[bburrill2012]

Well, guys, don't play with words like this, ok?

In this world, a radiator is the stuff we use for WC, otherwise we say "heatsink".

And don't start with "Yes, but the meaning of words...blah blah blah..." please, ok?

Do you want the new member to leave the forum already?

Is he not "elite" enough for you?

I was just being hard headed and my brain wasnt all there earlier.

Im not going anywhere. lol

 

[manu2b]

^Not talking about you (still a new member, aren't you?)

As I said: definition n°1 is me