2 x 200 mm fan yields the same temperature as 2 x 140 mm fan

Happy Hopping

Supreme [H]ardness
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Jul 1, 2004
Messages
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if you would advance to 5:18

and this is something I never look into. As I always assume a 2 x 200 mm fan would easily cool the case a lot more so vs. 2 x 140 mm fan.

But this graph shows 2 x 200 mm yields 66.2 deg C whereas 2 x 140 mm fan gives 67.2 deg. C

I would expect a much bigger gap than this 1 deg. C.

Has anyone own 2 x 140 mm at one time, measure your case temperature, and upgrade to 2 x 200 mm and measure it again for the difference?
 
There's a lot more to cooling than just fan size. Do the larger fans actually push more air into the case? Is airflow over the heat sinks or temp sensors improved, or does the extra air just go straight out the nearest vent? Would improved airflow actually be useful (i.e are the heat transfer surfaces of sufficient size to adequately transfer heat to the air that's passing over it, or can the material conduct the heat away from the source fast enough)?
 
same air flow, lower noise, that's the point of the 200mm and why theres barely a difference. how do you not know all these simple things youre asking about?!
 
no, I always buy the 200 mm fan because those dealers said it brings a lot more cool air into the case. I have 4 of them in my case and pay good $ for it. One of them is a 230 mm (side fan), the rest is 200 mm
 
I really wanted a 200mm fan in whatever case I ordered just for the hell of it size they are so huge and awesome looking.

But settled for 2x 140mm. Still move a ton of air
 
well, all the design today suck the intake air from the edges of both side. Older design a few yr. ago has a opening at the bottom w/ mesh wire, and air just goes right in (Phantom 820 form NZXT for e.g)
 
well, all the design today suck the intake air from the edges of both side. Older design a few yr. ago has a opening at the bottom w/ mesh wire, and air just goes right in (Phantom 820 form NZXT for e.g)
Not all designs do this. It's become something of a trend, but it's not ubiquitous.

Try an experiment. Calculate the ratio of the swept area of a 140mm fan to that of a 200mm fan, then calculate the ratio of the max RPMs of each and compare those two ratios. Tell us what you find.
 
that's the kind of calculation that I no longer remember how to do from university years.

Anyhoo, all these years, from dealerships, other retailer stores, I am always under the impression that bigger fan is always cooler. There is no reason to believe otherwise. Remember there was a PC case that the system fan is the lenght of the case? I forgot the name. It's like 2 ft. + long. Why do you think they make sys. fan that big if it's not cooler than a 14 cm fan
 
that's the kind of calculation that I no longer remember how to do from university years.

Anyhoo, all these years, from dealerships, other retailer stores, I am always under the impression that bigger fan is always cooler. There is no reason to believe otherwise. Remember there was a PC case that the system fan is the lenght of the case? I forgot the name. It's like 2 ft. + long. Why do you think they make sys. fan that big if it's not cooler than a 14 cm fan
If you can't remember how to do some simple algebra, (and even calling ratios algebra is a stretch,) maybe you're out of your depth pontificating the effectiveness of fans re: swept area size.
 
If you can't remember how to do some simple algebra, (and even calling ratios algebra is a stretch,) maybe you're out of your depth pontificating the effectiveness of fans re: swept area size.
Or maybe someone of your pedigree and intellect could redirect the couple moments you spent acting snarky to simply plop down the equation.
 
Or maybe someone of your pedigree and intellect could redirect the couple moments you spent acting snarky to simply plop down the equation.
*sigh* I was trying to encourage Hopping to do some critical thinking.

Noctua NF-A14
- 1,540 cm^2 swept area
- 1,500 rpm

Noctua NF-A20
- 3,140 cm^2 swept area
- 800 rpm

A 200mm fan of the same manufacturer and product line has roughly double the swept area, but half the max speed. That's why it's a wash. If they were both turning the same speed, yes the 200mm would move a lot more air.
 
that's the kind of calculation that I no longer remember how to do from university years.

Anyhoo, all these years, from dealerships, other retailer stores, I am always under the impression that bigger fan is always cooler. There is no reason to believe otherwise. Remember there was a PC case that the system fan is the lenght of the case? I forgot the name. It's like 2 ft. + long. Why do you think they make sys. fan that big if it's not cooler than a 14 cm fan
Univesity ?
Basic geometry and divsion are all prehighschool years... or is the state of
 
that's the kind of calculation that I no longer remember how to do from university years.
University ?

But how did you come up w/ the swept area ?
Prehigh school math/geometry classes.


Area of a circle = Pi * (radius * radius)
heck just to get the scale of the fans, you don't even have to know the math for the area of a circle. Just the most basic understanding that surface always increase X^2 compared to distance because we got from 1 dimension to 2 dimension

So the size in scale without knowing the right math for the geometrical shape would simply be 200^2 / 140^2 = ~2.0
aka twice the areas with half the speed = same shit.
 
But how did you come up w/ the swept area ?

https://noctua.at/en/products/fan/nf-a20-pwm/specification

it's not on the spec. sheet

anyhoo, I don't use Noctua, because back then, noctua doesn't have 200 mm. They recently add the 200 mm on thier product line.
And if you don't bother with the math you can just look at the airflow figure (which are in the specs) for both these fans. Then you'll realise why there's hardly any difference. They push 146m^3/h vs 140m^3/h at max rpm according to Noctua.
 
And if you don't bother with the math you can just look at the airflow figure (which are in the specs) for both these fans. Then you'll realise why there's hardly any difference. They push 146m^3/h vs 140m^3/h at max rpm according to Noctua.

I don't know why but this one just made me chuggle. All the smarty pants (me included) showing off math and all. and then you area ll just like:" or.... you can just read it here"
Touche...
 
I don't know why but this one just made me chuggle. All the smarty pants (me included) showing off math and all. and then you area ll just like:" or.... you can just read it here"
Touche...
OP presented evidence that suggested the similar airflow figures are accurate in his first post, then said that it couldn't possibly be right because 200 > 140. Then he argued with every rational reply as to why the airflow figures were similar.

This is, of course, Happy Hopping's modus operandi, and I'm a bit of a sucker for it. I don't know if he's legitimately trolling or just has a curious perspective on the world, but arguing with him is fun for me.
 
OP presented evidence that suggested the similar airflow figures are accurate in his first post, then said that it couldn't possibly be right because 200 > 140. Then he argued with every rational reply as to why the airflow figures were similar.

This is, of course, Happy Hopping's modus operandi, and I'm a bit of a sucker for it. I don't know if he's legitimately trolling or just has a curious perspective on the world, but arguing with him is fun for me.
I am unsure why you are telling me this ( Well at least the first part). the information seems redundant? am i missing something ?
 
I am unsure why you are telling me this ( Well at least the first part). the information seems redundant? am i missing something ?
I'm just saying that it's gone full circle twice, which is funny to me for I'm sure much the same reason that the airflow specs being listed on the product sitss is funny to you. XD
 
but are you guys forgetting the thickness of the fan from different manufacturers makes a difference? I don't have a noctua 200 mm, but I'll check the thickness of the ones I bought.
 
but are you guys forgetting the thickness of the fan from different manufacturers makes a difference? I don't have a noctua 200 mm, but I'll check the thickness of the ones I bought.
Why does it matter? A 200mm fan moves roughly the same amount of air as a 140mm fan. You practically provided proof in post #1, but still refuse to believe it. What are you trying to figure out here?
 
Why does it matter? A 200mm fan moves roughly the same amount of air as a 140mm fan. You practically provided proof in post #1, but still refuse to believe it. What are you trying to figure out here?

Check his post history... Seriously.
 
Why does it matter? A 200mm fan moves roughly the same amount of air as a 140mm fan. You practically provided proof in post #1, but still refuse to believe it. What are you trying to figure out here?

I am having a hard time believing it now, because sales people and those youtube reviewers of various fan setup videos have sold me the idea that bigger is better, and 200 mm is cooler than 140 mm, all these years. To suddenly acknowledge that 200 mm yields the same temperature as 140 mm, that takes a while to get used to.

and I paid more $ for those 200 mm fans back 4 yr. ago vs. those 140 mm fans.
 
200mm fans ARE cooler than lesser sizes.
You can put a bigger filter on which cuts down on cleaning frequency.
The larger diameter of airflow helps stir the stagnent air near the walls of the case.
Finally, just knowing that you have huge fans in your case gives one a warm fuzzy feeling of satisfaction.
 
I am having a hard time believing it now, because sales people and those youtube reviewers of various fan setup videos have sold me the idea that bigger is better, and 200 mm is cooler than 140 mm, all these years. To suddenly acknowledge that 200 mm yields the same temperature as 140 mm, that takes a while to get used to.

and I paid more $ for those 200 mm fans back 4 yr. ago vs. those 140 mm fans.
And yet, you have evidence that the two are comparable in your first post.

And of course you paid more for a 200mm fan; it's physically larger, requires a stronger motor, and is less popular than the smaller sizes. The price premium is easy to understand.

Bigger is better. But better doesn't always mean cooler. Better, as in this case, can mean as cool, but quieter. That's the real advantage of a 200mm fan. It can move the same amount of air as a 140mm at a much lower RPM.

You ever seen those giant industrial ceiling fans with 10ft blades? They move at something like 60 - 100rpm, and you can't hear them at all. They move tons and tons of air in an open space though. It's the same concept.
 
VanGogh, most good fans, whether it's 90 mm, 120 mm, 140mm or 200 mm are all fluid bearing. They are quiet. It may be "quieter" on a dB graph, but human ear can't hear them regardless. If I can't hear 16dB, and a 800 rpm 200 mm fan bring it down to 12 dB, it means nothing to me. There is no extra benefit

As to 140 mm fan, I do use Noctua, and I can't hear a sound from my PC case. So if the selling point in a marketing borchure pt. of view is "more quiet" on a 200 mm, it won't sell.

Those youtube reviewer people on 200 mm fan on PC cases in the past few years, they are the ones who said 200 mm are cooler than 140mm fan, and that video I post, is the only graph I've seen that shows otherwise. So maybe these youtube review people can fight it out
 
I give up. If you don't understand how an 800rpm fan could be quieter than a 1500rpm fan, I'm not gonna convince you of anything.
 
Also the airflow has a bigger hole to fit through so it whistles at a lower frequency.

Hmmm, hook up a mp3 player to the pwm signal to the fan and use as the 200mm fan as a 8" woofer.

Active noise cancellation even ?
 
Nobody can force the OP to understand the physics of fans. The math have already been gone through, and I pointed out that in the case of the different sized Noctua fans the end result of the math is already in the specs.

The simplified truth is that a fan provides cooling based on 2 main factors:
#1: The size of the fan blades. (See earlier in the thread for the math)
#2: How fast these blades are spinning. The manufacturer will tell you how fast, in rounds per minute (RPM), a given product is meant to rotate at it's operating voltage.

If you combine #1 and #2, you end up with the airflow. Which in turn is the cooling effect you will get out of said fan. Hopefully you will also understand why changing the RPM of the fan will change the airflow in your computer based on this. And this is the correct answer to the OP in this thread. The fans in the posted video are of different sizes and they rotate at different speeds, therefore the resulting cooling effect is close to identical!

What the airflow figure ignores is how noisy the fan is while producing said number. Two different fans with identical airflow figures can be wildly different when it comes to how loud they are and at what frequency that noise is.

We're also ignoring stuff like blade design/profile, and by extension thickness of fans, and the effect this have on airflow. I have not seen any mention of the fact that we have to subtract the area of the motor from the area of the fan to get a more correct value to calculate the airflow either (because the motor is not pushing any air after all).

Anyway, I'm not sure OP is really interested in correct answers. But if somebody else stumbles upon this thread while actually looking for proper answers, let's hope they learn something in the end.
 
Op if all you care about is temps, just swap the 2 200mm fans for 50 40mm fans.
 
This was such a fun thread to read. 10/10, would read again. Keep up this wholesome bantering.
 
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