Whats better?

[falloutguy]

Would 3 120mm fans be better than 2 140mm fans?

[Lays]

i think 3 120's since it'd be 360mm worth of fans vs 280mm but idk

 

ask @CoolBeans he has cool in his name so he must know about cooling

[WoodenMarker]

Depends on what you're using it for. For radiators, 120mm's tend to have better static pressure. 140mm's are good for moving a good volume of air while being quiet. 

If you're worried about noise, less larger fans would be best. If you don't care for noise at all and want maximum airflow, grab 3 deltas and get ready for liftoff. 

[falloutguy]

Depends on what you're using it for. For radiators, 120mm's tend to have better static pressure. 140mm's are good for moving a good volume of air while being quiet. 

If you're worried about noise, less larger fans would be best. If you don't care for noise at all and want maximum airflow, grab 3 deltas and get ready for liftoff. 

How loud are they though, I don't need something really quiet but i don't want anything annoying.

[zip2k4]

I want to say 120s since you do get quieter (for most fans) operation and depending on which fans you'd get - potential for tighter airflow as well (directed airflow)

[WoodenMarker]

How loud are they though, I don't need something really quiet but i don't want anything annoying.

I only brought up delta fans as a joke. They are really loud.

http://www.youtube.com/watch?v=KmDGPFLoPwc

 

There are both quiet 120mm and 140mm fans. Whichever you get should really just depend on the pricing. 

[D3MON]

delta fans are only loud at 12 v when you pick high ariflow options, ALL HIGH CFM FANS ARE LOUD AT !"V but they cooler better for a given voltage/speed than others i find, the only downside is theyre not pretty like most fans (except noctuas) theyre just black fans designed to move air as good as possible, if you look at the heatsink on an amd chip or xbox and various others changes are its a delta (ive even seen them in powersupplys) check out thier website, theres no fancy graphics or animations, theyre all business about cfm and mm of pressure.
the 80x25mm fan on my am2+ cooler for instance in running is near silent (seriously its the quietest fan ive ever heard). the reason people think theyre loud is because they hear stories of super loud and super powerful deltas (insert delta airlines joke) and they get one and put it at 12v and are loud "urrr yeah they are loud ahuc, ahuc".

http://www.deltaww.com/Products/CategoryListT1.aspx?CID=0304&PID=ALL&hl=en-US
http://www.youtube.com/watch?v=JfohzD2skm8
assuming a 120mm fan has a 120mm diameter that gives and area of 120/2=60mm, 3.142(pi)x60x60=11311mm sq
that said a fan has a motor, assuming that 1/3 of the fans diameteris motor (lets call this a standard motor) it would be 40/2=20mm, 3.142x20x20=1256.8mm sq
11311-1256.8=10054.2mm sq

with a 140mm fan assuming again that the motor was 1/3rd of the fan area (not too common, most 1400mm fans use standard motors from a 120mm fan line) it would be
140/2=70, 3.142*70*70=15395.8mm sq
46/2=23, 3.142*23*23=1662mm sq
15395.8-1662=13773.8

so a 140mm fan would have a 30% advantage thats if the motor was increased in size, allot of fans keep the same motor and just increase swept area.
which would (cutting out the math) give 14139sq mm of swept area.
2x140mm fans would equal-27547mm sq of swept area (with the larger motors)
2x140mm fans (with the standard sized motor) equals 28278mm sq of swept area (with standard motors)
3x120mm fans would equal 30162.6mm sq of swept area.

so here 3x120mm fans will give a small benefit (when i say small i mean 6.6%), this doesnt take into effect the design of the fan blades being shaped differntley to accomdate the altered sweep, it also doesnt take into account that a 120mm fan would need to spin 40.6% faster to move the same amount of air.
static pressure largely depends on fan rpm, blade pitch, blade area, motor housing design (number of fans pushing together but thats obvious). B) 

whats the application?

[CthulDude]

Depends on what you're using it for. For radiators, 120mm's tend to have better static pressure. 140mm's are good for moving a good volume of air while being quiet. 

If you're worried about noise, less larger fans would be best. If you don't care for noise at all and want maximum airflow, grab 3 deltas and get ready for liftoff. 

This sums it up nicely. Three average 120mm fans would move more air than two 140mm but would be louder. Infact, the larger the fan gets the quieter it gets cause it takes less RPM to create equal CFM over a larger area. Just don't expect larger fans to create static pressure, cause they would require a high RPM and be massively loud. Unless you're going for the aesthetics of two 140mm, which does look nice, I would go with three 120mm.

[DrainDoc]

Would 3 120mm fans be better than 2 140mm fans?

I would think that it depends upon the application they are being used for, and the type of fan they are.

 

Like, if you are comparing, lets say a Rosewill Fan to a Corsair or Noctua Fan. It's night and day.