fan sizes and noise

Discussion in 'Cases & Cooling' started by pmv, Dec 16, 2012.

  1. pmv

    pmv Golden Member

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    This may be an impossible question to answer at a very general level, but just in case...

    Which is considered to be better in terms of noise-level-for-same-amount-of-air-shifting? A large fan or several smaller ones?

    I googled it but what I found gave me a headache (full of graphs with unlabelled axes and mysterious acroyms!).

    I would guess that the larger fan would be quieter, but I don't know.

    Being more specific, I'm trying to guess which would be quieter for same cooling, the corsair 200r with potentially as many as 8 12cm and 14cm fans, or the haf 912 with a couple of 20cm ones plus a 12 and 14. But also curious about the question in general.

    Also wondering if logically one wants different characteristics in an intake vs an extractor fan?
     
  2. dma0991

    dma0991 Platinum Member

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    You should probably stick with 120mm fans, you'll be spoilt for choice compared to 140mm and bigger fans. The bearing and motor quality does play an important role and 200mm/230mm fans are not the best choice. Popular choices could be Yate Loon, Aerocool and Arctic Cooling to name a few.

    Having 8 fan slots does not mean that you need to populate every single one of them to get the most. Just do the bare minimum of 2 front intakes and 3 top/back exhausts. Less fans = less likely to be noisy. The case temp difference between populating every slot versus the method I've mentioned is negligible.
     
  3. Zap

    Zap Elite Member

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    This.

    Also, lower RPMs = less likely to be noisy.

    Basically, a case that is a windtunnel will be noisy.
     
  4. Vinwiesel

    Vinwiesel Member

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    The larger fans not only produce less noise, but it is at a lower pitch and less annoying than smaller fans. If you are running a single video card, and a moderately overclocked cpu, you honestly don't need a great deal of fans. Just be sure you have positive pressure (more intake than exhaust) so the warm air exits the case reliably.

    Since most modern motherboards have built in fan control, I am running 1200rpm 120/140mm fans which are a little noisy at full speed, but are nearly silent after the motherboard throttles them down. I also run the classic front to back airflow.

    Most importantly, you need good coolers on your CPU and Video card to start with. Trying to force tons of air through a case to compensate for a poor cooler will be a losing battle. On my first build I made the mistake of going cheap on the CPU cooler, so it was just wasted money when I had to replace it with a quality unit.
     
  5. Zap

    Zap Elite Member

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    You are comparing size in regards to airflow. Pitch comes from the RPM that the fan spins at, and is related to "annoying noise." Larger fans produce less noise and at lower pitch because they can be run at slower RPMs to produce similar airflow as a smaller fan at higher RPM. Run an 80mm fan and a 120mm fan at the exact same RPM and let us know what you think as to how they sound. :hmm:
     
  6. Rikard

    Rikard Senior member

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    Correct. Ultimately you need to provide a certain minimum airflow, and you either get that by fast spinning small fan, which produces a high pitched sound, or a slow spinning large fan, which produces a deeper tone. For that reason I prefer 14 cm fans, I do not know about 20 cm or larger ones though.
    No, that is not true. If you can spin two fans slowly to generate the airflow you need you often get less noise in total than if you have one fan that needs to spin faster. Also, in my case I use one intake and one exhaust linked to the GPU temperature, which results in that my GPU fan spins much slower than with the case fans turned off. It makes the system as a whole more silent.

    It is better to start with how much airflow you need, then find a way to provide it with minimum additional noise.
     
  7. dma0991

    dma0991 Platinum Member

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    That is only true if you have a fan controller to limit the fan speed which most often people do not consider buying. If the speed is regulated by the motherboard which ramps up according to load, less fans = less noisy holds true. Plus, you cannot escape the fact with more fans, you are more likely to run into mechanical problems like bearing noise from worn out fans.

    Unless you have your GPU in a tunnel shroud with intakes and exhausts in both ends, you can't claim that your GPU is liked with the case fans. There is no measurable way of knowing how much airflow you need. All the case fans does is to keep the air moving in and out of the case.

    You can do with 1 intake and 1 exhaust and it still gets the job done. Adding more fans to 2 intake and 2 exhaust does not reduce case temps by half. An optimistic figure would be ~3C less at best. Changing case fans has very little difference compared to changing a better heatsink for your CPU or GPU, fact.
     
  8. Rikard

    Rikard Senior member

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    I was under the opposite impression that nobody runs all their fans at 12 V anymore, but I guess neither of us has any actual statistics on that it becomes too speculative to take further.

    Yes, the more mechanical parts one uses the larger chance that at least one of them will fail.

    I think you misunderstood me. I am using SpeedFan to read the GPU temperature, which is used as input parameter to a fan curve for CHA1 header (4-pin non-PWM), and CHA2 (3-pin) is just a slave of CHA1. One of the fans is blowing cold air directly onto the graphics card, the other is helping the back fan evacuate the additional heat generated by the GPU. When GPU temp reaches 40 C, Speedfan sends 37% power to the fans, which is the fan's starting voltage. From their on it slowly increases the fan speed with increasing GPU temperature. I do not remember the numbers by heart, but the GPU fan must work a lot harder (thus causing much more noise) if I do not use the two chassi fans to pull cold air over the graphics card. Optimal working point for noise and cooling can be found by tuning fan curves of chassi fans and GPU fan for load and idle. It is a very real effect.
     
  9. dma0991

    dma0991 Platinum Member

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    It could be, under a very limited circumstance. As for me, I'd rather have my temps controlled by hardware without software intervention as SpeedFan does not work for different types of OSes. I'd rather be fiddling with watercooling than fan profiles. Watercooling works very well with GPUs in terms of noise and temps. Since I'm channeling the heat elsewhere and I get the flexibility of dumping the heat externally, case temps is less of problem to me.
     
  10. pmv

    pmv Golden Member

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    Thanks for responses.

    By the way, I have a fan controller and it would be going in any new box. I guess part of what I was asking was 'would more or larger fans let me run them all slower hence less noise?'. And, indeed, whether 'more fans' or 'larger fans' was the better way to do that.

    While I'm at it - are these self-contained closed-loop cpu water coolers any good? As they tend to have 12cm fans and not-particularly-big radiators, I'm wondering if they actually do anything to reduce noise compared with a decent conventional cpu cooler?
     
  11. Red Squirrel

    Red Squirrel Lifer

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    I prefer big fans to small ones. Big fans move more air than a small fan of the same speed so you can slow them down. When big fans are loud the pitch is also not as annoying.

    I still remember my AMD 2000+, first computer I built. The stock fan was a small blue 60mm fan for the cpu. That computer sounded like a vacuum cleaner!

    The issue today is video cards though, they need multiple fans and they tend to spin very fast.
     
  12. philipma1957

    philipma1957 Golden Member

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    http://www.newegg.com/Product/Produc...82E16835553006

    I got these at 8 bucks a piece they move air they allow speed controls quiet or louder .


    I run them in my cooler master elite 120 case.

    They can do both the cpu and the intake fan.


    yeah 200cm fans are nice but no choice compared to 120mm
     
  13. coffeejunkee

    coffeejunkee Golden Member

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    It depends what you value more, idle or load noise. In general, smaller fans can go down to a lower rpm than large fans before coming to a complete stop. Under load, larger fans move more air than smaller fans for the same noise.

    As for the aio-watercoolers, I wouldn't recommend them. Apart from the H100, normal aircoolers offer better price/performance/noise ratio. Reason many people do get the smaller ones is because of looks or to be able to use ram with big heatspreaders (which is basically for looks too, since ram doesn't get very warm at all).
     
  14. Rikard

    Rikard Senior member

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    I do not think one can make a blanket statement that fits all cases here. It depends on the layout, meaning how the fan is interplaying with other fans, and where the air is supposed to be directed at. In my case, using a 14 cm fan blowing cold air directly onto the graphics card works wonders, especially since it turns itself off when the graphics does not need the extra cold air. YMMV
     
  15. Eureka

    Eureka Diamond Member

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    Space and weight, too. You can move the radiator anywhere, and it doesn't strain the mainboard like a noctua does.
     
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