1 big fan or 2 smaller fans for cooling

[rds1220]

Ok I just confused myself even more now. For overall cooling of the computer interior is it better to have one big fan such as a 200mm or two smaller fans such as a 140mm X2. I have read different reports and it seems everyone has a different answer. Some people seem to say one big 200mm fan going at a low RPM will give better cooling then two or three smaller fans. Other report that they had better cooling with two smaller fans going at a slightly higher RPM.

This is my situation related to the question above. I have a Corsair Obsidian 650D Mid Tower. Its still pretty big for a mid tower but thats what I like about it. The front fan is 200mm and it can not be replaced with any other size. So I'm taking the stock one out and putting in a Cooler Master Megaflow 200mm LED fan. Now for the top exaust I don't know what to do. It comes with a 200mm fan. I don't know if I should leave it as a 200mm or mount 2 140mm fans. Again it will depend on the question above. Which get better cooling.

 

[Outlander_04]

generally bigger slower fans make less noise .

If I was you I would leave the case as it is and if there is a heat [ or noise ] problem when your computer is running then make a decision on how to fix that

 

[AdrianPerry]

The best cooling is going to come from whichever combination will push more CFM.

Generally 2 smaller fans will spin faster and push more air through. Certainly between a single 200mm or x2 140mm, the two 140mm fans are going to be pushing through air much more quickly than a single 200mm.

The higher the CFM - The more air will be pushed through the fan per minute.

As Outlander_04 said though, bigger fans can do the same job and move "enough" air, while generally remaining quieter.

 

[Outlander_04]

Area a circle A = Pi times r squared

A 200 mm fan has 0.0314 square meters area [ believe me I did the math ]

a 140 mm fan has 0.015 square meters , but there are two of them so 0.030

The single 200mm fan has more area [ just] than two smaller fans , and even more again when you consider that all three fans have a similar size hub sizes and you lose that area twice with the smaller fans .

Also if a 200 mm fan is spinning at the same speed as a 140 mm fan the tips of the blades are moving much faster . This is part of the reason why a larger fan doesnt have to spin so fast to move more air . A bonus of that is that it then makes less noise

One big fan , not two small ones

 

[joshyboy82]

Thumbs up that ^

 

[AdrianPerry]

Area a circle A = Pi times r squared

A 200 mm fan has 0.0314 square meters area [ believe me I did the math ]

a 140 mm fan has 0.015 square meters , but there are two of them so 0.030

The single 200mm fan has more area [ just] than two smaller fans , and even more again when you consider that all three fans have a similar size hub sizes and you lose that area twice with the smaller fans .

Also if a 200 mm fan is spinning at the same speed as a 140 mm fan the tips of the blades are moving much faster . This is part of the reason why a larger fan doesnt have to spin so fast to move more air . A bonus of that is that it then makes less noise

One big fan , not two small ones

I presumed this would be true of x2 120mm fans vs 200mm fan, but I'm surprised to see that result with x2 140mm fans? Their surface area surely is far larger than a single 200mm?

 

[pjmelect]

One big fan every time.

 

[cats_Paw]

For a case id go with a big fan. Especially becouse static pressure is not something very important.

 

[Rizlla]

I would say one big fan. It spins slower which means less noise and it will move about the same amount of air as two small fans.

 

[Outlander_04]

I presumed this would be true of x2 120mm fans vs 200mm fan, but I'm surprised to see that result with x2 140mm fans? Their surface area surely is far larger than a single 200mm?

Pi times r squared

area increases with the square of the radius , so diameter increases produce large changes in area

 

[AdrianPerry]

Hmm guna do the math and write it out here to see the outcome

Pi (3.142) x Radius ((70mm)140mm fan) Squared
Effectively 70x70x3.142
= 15395.8
Now x2 (because there would be x2 140mm fans)
= 30791.6

Ok so now the 200mm fan:

Pi (3.142) x Radius ((100mm)200mm fan) Squared
Effectively 100x100x3.142
= 31420

---

Ah you were right, fair enough The results are fairly close, but I have to say I'm shocked by the outcome.

Outlander_04 and the math proves a single 200mm fan = better than x2 140mm fans In terms of actual temperature, I think the difference would be down to less than 1 degree. So either option would work. However based on the low noise of a 200m - probably the best choice

 

[Guest]

Or get a 240mm fan like me and stic at the side of you case. And get a 200mm fan and stic in in the front.