Whats better 3 120mm or 2 140mm fans?

[Th1rtyS1x]

was planning on upgrading my case and giving my old one and fans to my father and was planning on picking up some noctua fans with the case and wanted to know if 2 140mm would be better than 3 120mm fans in the front

[GuiltySpark_]

Ultimately, without the exact specs of the fan's we can't answer that. However if you can fit 140mm fans, I would do that. You can have them spin slower and produce less noise as a result. 

[Beerzerker]

3 120's would be better overall, more CFM by volume with the extra fan, provided fan speeds between them are about the same.

[Th1rtyS1x]

1 minute ago, rickeo said:

Ultimately, without the exact specs of the fan's we can't answer that. However if you can fit 140mm fans, I would do that. You can have them spin slower and produce less noise as a result. 

phantex p500a, coming from a fractal design define c with 2 120mm FD fans in the front, never played with the fan curve as i dont have any knowledge in this field, am just asking if 120 would move more air or is 140 better

 

[WhitetailAni]

3 120mm if you care about airflow, 2 140mm if you care about noise.

[Analog]

34 minutes ago, Th1rtyS1x said:

phantex p500a, coming from a fractal design define c with 2 120mm FD fans in the front, never played with the fan curve as i dont have any knowledge in this field, am just asking if 120 would move more air or is 140 better

 

 

If you are talking about intake fans, your case should be able to support 3x 140mm fans in the front. That will certainly be better than 3x 120mm or 2x 140mm fans. 

[Beerzerker]

32 minutes ago, Th1rtyS1x said:

phantex p500a, coming from a fractal design define c with 2 120mm FD fans in the front, never played with the fan curve as i dont have any knowledge in this field, am just asking if 120 would move more air or is 140 better

 

Think for a sec.....
By volume, a 140 on it's own will outdo a 120 provided the fanspeed is the same since there is simply a larger fanblade in use with the 140, which means more air by volume is being moved.

However when you add up the CFM each fan can move at the same speed is where the difference is.

3 120's vs 2 140's will move more air since 3 120's equals 360mm worth of fan period and 2 140's equals 280mm of fan in use.

You can ramp up the 140's in fanspeed to match the 120's but that in turn will make more noise to get it. You'll also need to run them faster as in noteably faster just to equal the CFM the 120's would be moving at their stock speed...
Then if you want, just run up the 120's a little and they are back on top and still run with less noise since they won't have to be ramped up as far in speed per individual fan to get ahead again in CFM's moved.

For a quiet system that moves more air by volume/CFM at the same fan speed, 3 120's are better for that if you can fit them into the case.
If you don't mind the noise, 140's can do just as well but will be louder.

The above says you can fit 3 140's, that would be the best you can do if you can get them in and running.

[Th1rtyS1x]

1 minute ago, Beerzerker said:

Think for a sec.....
By volume, a 140 on it's own will outdo a 120 provided the fanspeed is the same since there is simply a larger fanblade in use with the 140, which means more air by volume is being moved.

However when you add up the CFM each fan can move at the same speed is where the difference is.

3 120's vs 2 140's will move more air since 3 120's equals 360mm worth of fan period and 2 140's equals 280mm of fan in use.

You can ramp up the 140's in fanspeed to match the 120's but that in turn will make more noise to get it. You'll also need to run them faster as in noteably faster just to equal the CFM the 120's would be moving at their stock speed...
Then if you want, just run up the 120's a little and they are back on top and still run with less noise since they won't have to be ramped up as far in speed per individual fan to get ahead again in CFM's moved.

For a quiet system that moves more air by volume/CFM at the same fan speed, 3 120's are better for that if you can fit them into the case.
If you don't mind the noise, 140's can do just as well but will be louder.

thanks, and im new to this so i came here for help from people with greater knowledge than me thats why

[Th1rtyS1x]

3 minutes ago, Analog said:

 

If you are talking about intake fans, your case should be able to support 3x 140mm fans in the front. That wills certainly be better than 3x 120mm or 2x 140mm fans. 

yes but i would have to open the bottom shroud and i have 2 HDD's so the wouldnt fit unless i mash my drive bay right up against my PSU

[WoodenMarker]

It depends on the fans and what you're aiming to cool. If what you're cooling is primarily above the psu shroud, 2x 140mm's are probably fine. 

[thrasher_565]

not all 140mm fans are quieter then 120mm fan just depends on fan and at what rpm.

[tkitch]

9 hours ago, Beerzerker said:

Think for a sec.....
By volume, a 140 on it's own will outdo a 120 provided the fanspeed is the same since there is simply a larger fanblade in use with the 140, which means more air by volume is being moved.

However when you add up the CFM each fan can move at the same speed is where the difference is.

3 120's vs 2 140's will move more air since 3 120's equals 360mm worth of fan period and 2 140's equals 280mm of fan in use.

And you just flunked geometry.

You forgot the X Axis (Y Axis?  Pick one.)

120x360 = 43,200

140x280 = 39,200

 

So, is it more area with 2x 120's?  Yes, but not by nearly as much as you're suggesting, it's roughly 11% Difference.  (whereas 360 vs 280 is nearly a 30% jump)

[wONKEyeYEs]

9 hours ago, Beerzerker said:

3 120's vs 2 140's will move more air since 3 120's equals 360mm worth of fan period and 2 140's equals 280mm of fan in use.

It doesn't work that way, you comparing linear measurement to area.

 

120mmDia = 11,304mm sq
3x120mmDia = 33,912mm sq

 

140mmDia = 15,390.9mm sq
2x140mmDia = 30,780mm sq

 

360mmDia = 101,736mm sq

[Blue4130]

It also matters on the blade design and housing. You can have a 120 that moves more air than a 140 if the blades are designed to do so. Without exact fan specs, it's not possible to say for certain which is better. 

[thrasher_565]

question is if you fit 3x120mm fans vs the 2x 200mm fans the 3 would out preform

Edited May 14, 2021 by thrasher_565

[RejZoR]

For cases, larger fans are always better. They are never that restricted to require insane pressure, but larger fan blades generally make less noise. For heatsinks and radiators, smaller fans are generally better because they produce higher pressure at lower speeds.

[Beerzerker]

3 hours ago, tkitch said:

And you just flunked geometry.

You forgot the X Axis (Y Axis?  Pick one.)

120x360 = 43,200

140x280 = 39,200

 

So, is it more area with 2x 120's?  Yes, but not by nearly as much as you're suggesting, it's roughly 11% Difference.  (whereas 360 vs 280 is nearly a 30% jump)

So sorry I was never a math wiz.....

Seriously.
BTW I'm not taking this as an "Attack" towards me.

I still say IF fan speed IS the same and the fans are rated accordingly in comparision to each other it comes down to total CFM moved.
However the difference in size is relevant, that I can't deny but even with that 11% is still 11% more. I get what you are after here but from my years of doing this I've had better luck overall with setups ran as I suggested.
All I can do is suggest what I've experienced, nothing more since it held true for me.

However....
If you can move more air in CFM with the two larger fans that's the way to go.
 

[LogicalDrm]

-> Moved to Cooling

[freeagent]

I like 120x38s..

 

This way I never have to have this conversation.