2 Smaller fans vs 1 Large fan

[jji7skyline]

Which is better in terms of Sound to Performance ratio? I'm thinking of getting either:

2x80/92mm fans OR
1x120/140mm fan

Two of these configurations for intake and exhaust, so a total of either 2 or 4 fans.

 

[BonzaiDuck]

Which is better in terms of Sound to Performance ratio? I'm thinking of getting either:

2x80/92mm fans OR
1x120/140mm fan

Two of these configurations for intake and exhaust, so a total of either 2 or 4 fans.

If it were me, at this day and age of case and fan choices, I simply wouldn't deploy any 80mm or 92mm unless there is some peculiar, draconian requirement for it.

Larger fans may mean greater CFM airflow at lower RPM (and lower noise dBA), but they also come with less static pressure. In a typical computer case, I'd use the largest fans for air-intake and smaller fans for CPU and exhaust. I can offer two examples: My HAF 922 cases are equipped with two 200mm fans each for intake, a single 120mm CPU heatpipe "pusher" fan with the heatpipe ducted to a 120mm exhaust fan; the system I just recently built for my brother uses an older ATX case with insufficient intake -- a 120mm at case bottom-front. In that latter example, I decided to use three 5.25" drive bays as wind-tunnel for a 140mm Akasa Viper -- to enhance the intake air. The remainder of bro's configuration was identical to what I'd done with the HAFs.

 

[Cerb]

120/140, hands-down. Getting to 180mm+, you can end up getting some noise even at lower RPMs like the wub-wub-wub-wub of ceiling of floor fans, but that tends not to be a problem from 140mm and down.

But, you may not need all 4...

 

[jji7skyline]

I think I'm going to reuse the two 92mm fans I have for exhaust, then buy either a Noctua Redux 140mm or 120mm PWM fan or both for intake.

Thanks for the input guys, really appreciated. If I think the 92mm fans are still too noisy I'll switch them over to Noctuas too.

 

[Essence_of_War]

Which is better in terms of Sound to Performance ratio? I'm thinking of getting either:

2x80/92mm fans OR
1x120/140mm fan

Two of these configurations for intake and exhaust, so a total of either 2 or 4 fans.

It depends on the particular fans and their exact speeds, but generally, 120/140mm fans will give you MUCH better perf/dB than 80/92mm ones. What case are using, and do you have particular fans in mind?

 

[jji7skyline]

It depends on the particular fans and their exact speeds, but generally, 120/140mm fans will give you MUCH better perf/dB than 80/92mm ones. What case are using, and do you have particular fans in mind?

I'm actually doing a PowerMac G5 mod, so I would be reusing the two 92mm fans in the back rewired to run at a fixed speed on 5V.

 

[Aikouka]

Are you really sold on the Noctua fans? I mean... I'm pretty sure you could buy two 140mm fans from another brand for pretty close to what you pay for one Noctua fan. Noctua fans are usually quite good, but they're also quite pricey. I also wouldn't necessarily push for one if it's just for airflow -- maybe if you're looking at a high static-pressure-required situation (e.g. radiator).

 

[BonzaiDuck]

120/140, hands-down. Getting to 180mm+, you can end up getting some noise even at lower RPMs like the wub-wub-wub-wub of ceiling of floor fans, but that tends not to be a problem from 140mm and down.

But, you may not need all 4...

Did you actually have a first-hand experience of "wub-wub-wub" with the 180-plus-ers?

Those that I had originally came with the HAF cases. I made a decent effort to shop for replacements -- whatever the price -- based on what I knew about fans in general. At idle, they're all running at ~400RPM. I never heard anything, either with the limpo CM "LED" fans or the better ones. I DID have one die, after maybe three years . . .

Other than the fact that they're just "large" and that the static pressure is lower, bigger fans mean at least a certain case-size and volume. Everything else in this technology points to smaller cases.

Some of us were just born to be helicopter pilots. I just turn on my computer . . . "We're flying low over Kontum province (wop wop wop wop wop . . . ) I was on a special mission! I'm Sergeant Fury!!" {wop wop wop wop wop)

But . . . "Wub wub wub??!!" :biggrin:

 

[bigboxes]

I got into computers before the 80mm era. I can assure you that you don't want to go back to smaller fans. I bought 80mm stealth fans and they were nothing compared to 120mm+ fans as far as air movement and dB. Whomever made the Noctua comment needs to have his head examined. If you want silence and reliability you definitely need to get a Noctua fan. I've got two in my new rig and they are dead silent and pushing some serious wind.

 

[BonzaiDuck]

I got into computers before the 80mm era. I can assure you that you don't want to go back to smaller fans. I bought 80mm stealth fans and they were nothing compared to 120mm+ fans as far as air movement and dB. Whomever made the Noctua comment needs to have his head examined. If you want silence and reliability you definitely need to get a Noctua fan. I've got two in my new rig and they are dead silent and pushing some serious wind.

I"ll agree with that view of Noctua. Noctua tried every trick in the book to improve airflow at lower RPMs and amperage. Personally, I still thought their fans were a bit limp for airflow, but the iPPC models might be my future choices for some applications.

I corresponded briefly with one of their engineers in tech-support, to ask a question about one of their CPU coolers. They were quite candid that "their customers" were more partial to lower dBA ratings at the expense of higher CFMs.

The iPPC fans may be expensive, but they're worth it for certain purposes, in my opinion.

 

[XavierMace]

I"ll agree with that view of Noctua. Noctua tried every trick in the book to improve airflow at lower RPMs and amperage. Personally, I still thought their fans were a bit limp for airflow, but the iPPC models might be my future choices for some applications.

I corresponded briefly with one of their engineers in tech-support, to ask a question about one of their CPU coolers. They were quite candid that "their customers" were more partial to lower dBA ratings at the expense of higher CFMs.

The iPPC fans may be expensive, but they're worth it for certain purposes, in my opinion.

I find the iPPC-3000 (140mm) to work great on my radiator.

 

[Aikouka]

Whomever made the Noctua comment needs to have his head examined. If you want silence and reliability you definitely need to get a Noctua fan. I've got two in my new rig and they are dead silent and pushing some serious wind.

You do not need a Noctua fan to get decent airflow at low RPMs with low to non-existent noise. This comes from trying out many different brands of fans including Noctua. I cannot stand computer noise, and I won't put up with noise from fans. Do I think Noctua fans are good? Yes, but are they required? Heck no!

 

[Yuriman]

SPCR ranks Noctua's fans pretty well, but Nexus, Scythe, GELID, Noiseblocker and Be-Quiet! all have competitive offerings are competitive (or lower) prices.

I run Noctua fans in my computers currently, but it was largely due to lack of availability of other good non sleeve-bearing fans, because of Noctua's impressive warranty, and the included accessories. Amazon, for instance, overcharges for Noiseblockers and Be-Quiet fans, and Nexus fan bearings will degrade within a year or two if run in a horizontal orientation. However, Nexus fans (or Yate Loons, same thing) may be better choices for most due to their cost effectiveness.

 

[Subyman]

Gotta think surface area with fans. Surface area goes up with the square of the radius, so it increases quite fast as you go up in size. A 120mm fan is over 2x the surface area of a 80mm fan. In very, very basic terms (not completely real world) an 80mm fan would have to work over twice as hard to move as much air as a 120mm fan.

 

[xthetenth]

You need a high quality fan for silence and reliability. This does not necessarily mean a Noctua but they are one very good option. I'm running their fans on one of their huge heatsinks because it's a good pick for a heatsink for cool performance on a relatively low wattage part.

And yeah, at constant RPM tip velocity goes up as a factor of radius, area goes up as a factor of radius squared. So if you hold airflow (proportional to area) constant, air noise is the same, but noise from turbulence and rotational speed decrease linearly with an increase in radius. So that stuff just about gets halved going from an 80mm to 140mm fan. And airflow noise is really easily ignored white noise. My case has 2 140mm exhausts, a 200mm intake and 2 140mm heatsink fans, and the only noise that isn't my PSU being a jerk is airflow.

 

[Cerb]

Did you actually have a first-hand experience of "wub-wub-wub" with the 180-plus-ers?

Silverstone and Phobya.

But . . . "Wub wub wub??!!" :biggrin:

That light air chopping sound you can't hear with small fans, but readily can with bigger ones. Like meow, it's not exact, but close...

 

[MongGrel]

Larger is usually better.

And I have to admit to spending a bit more money on a few Noctua fans here and there, I love the things myself.

*shrug*

 

[Cerb]

They're good fans. I spent quite a bit on them for my PC. But, they are pricey for what they are. I bought them because I've been out of the loop a bit, couldn't find clear Slipstream replacements, and did not want to get fans, like Nexus/YL quiet fans, or Slipstreams, that will start having problems after running for a few years. OTOH, $15-20/ea. for 120mm fans, with accessories I really don't want or need, kinda rubs me the wrong way, at the same time.

 

[BonzaiDuck]

Silverstone and Phobya.
That light air chopping sound you can't hear with small fans, but readily can with bigger ones. Like meow, it's not exact, but close...

I never used fans that size from either manufacturer. Do they use sleeve, rifle, . . . dual-ball . . . hydrodynamic . . ?

How did you mount the fans? Self-threading screws, machine nuts/screws -- rubber-mounts or other custom noise-isolating method?

 

[bigboxes]

You do not need a Noctua fan to get decent airflow at low RPMs with low to non-existent noise. This comes from trying out many different brands of fans including Noctua. I cannot stand computer noise, and I won't put up with noise from fans. Do I think Noctua fans are good? Yes, but are they required? Heck no!

I never said they were required. There are alternatives that work well. My point is that Noctua has a well deserved reputation and the quality/performance is worthy of their cost.

 

[BonzaiDuck]

You do not need a Noctua fan to get decent airflow at low RPMs with low to non-existent noise. This comes from trying out many different brands of fans including Noctua. I cannot stand computer noise, and I won't put up with noise from fans. Do I think Noctua fans are good? Yes, but are they required? Heck no!

Well, first to answer Biggie: I look for CFM and manageably lower noise level. Noctua is one of a handful of options for me. For specific purposes, however, I'd pick a Noctua iPPC. I might look at Akasa Vipers, Cougar Vortex, Scythe and some other models that the noise-obsessives favor.

But my systems are virtually noiseless. If they approach some threshold with some residual white noise, the surround-sound and other aspects of use assure that I still hear nothing, even at modest volume settings.

The biggest problem I have with the iPPC models is their expense. $30 a pop, last I looked or "checked out."

 

[Yuriman]

They start at around $24 on Amazon, while Noctua's other fans start at around $14.

 

[Cerb]

I never used fans that size from either manufacturer. Do they use sleeve, rifle, . . . dual-ball . . . hydrodynamic . . ?

Silverstone loves sleeves, so probably that for theirs, but I'd have to go look that up. They are long gone from my hands, now.

How did you mount the fans? Self-threading screws, machine nuts/screws -- rubber-mounts or other custom noise-isolating method?

Screws. Well-balanced fans really don't get much, if anything, from isolation, unless being run from a slow PWM controller.

The biggest, "problem," I think, is that they can cool such powerful computers at fairly low RPMs, so there isn't turbulence, or bearing noise, to mask it, and no need for other fans to be spun up higher. A single 180mm+ fan can handle pretty much any single-GPU stock-speed system today at 500 RPM or less, with just little help in exhausting from the PSU and video card fans.

 

[BonzaiDuck]

Silverstone loves sleeves, so probably that for theirs, but I'd have to go look that up. They are long gone from my hands, now.

Screws. Well-balanced fans really don't get much, if anything, from isolation, unless being run from a slow PWM controller.

The biggest, "problem," I think, is that they can cool such powerful computers at fairly low RPMs, so there isn't turbulence, or bearing noise, to mask it, and no need for other fans to be spun up higher. A single 180mm+ fan can handle pretty much any single-GPU stock-speed system today at 500 RPM or less, with just little help in exhausting from the PSU and video card fans.

I choose to isolate them with rubber any way I can, regardless -- most especially if they're mounted in a side-panel, but otherwise without exception. If a sleeve-bearing fan "comes my way," I won't use it.

The noisiest fan I use is a GT AP-30 4,200RPM. I chose it for "airflow flexibility." My system configurations assure they won't run above 3,600. At that speed, there will be "white-noise" -- the rush of air you might hear from an AC vent on a hot day. The more noticeable motor noise has been erased with ducting to which I added a few layers of Spire. But in real-world usage -- gaming, for instance -- there's nothing of the AC-vent, nor anything else.

I'd be really curious to hear one of those Silverstone of Phobya units and the "wub wub wub" you described, though. If your description is correct, it will make me think twice about buying one. I'd entertained getting one or more of those Phobya 180's.

I KNOW that my noise-isolation practices attenuate a lot of noise transmitted to the case by fans. What I find even more annoying is unisolated HDDs. Put four or more in a computer case without rubber mounts -- the "Hmmmmm" is amplified and pronounced. I hate that . . . .

 

[Cerb]

AFAIK, the only way to avoid such noises existing is to be far away, or have more and more fins, assuming no RPM increase. If I put my head up to my PC's current Noctua P12s, when they are running <400 RPM, I can hear the same sort of thing. Difference is that one I can hear from 2-3 feet, and the other <3 inches .

Yeah, I've got a Purple (Red w/ different firmware), and still had to isolate it. One of these days I'm just going to build a USB3 DAS box, or something, to put HDDs in a closet, without losing half the copy speeds .