How quiet is QUIET?

Ocean said:
i wonder if the 360mm fans will ever take hold as great for the side access panel.


im hoping corsair will make a case featuring one of these.
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Considering most people don't like 230mm fans much, I doubt it. 230mm fans have great CFM to noise ratings, but terrible static pressures. With how close they are to GPU's they simply don't seem to have the pressure to overcome the tight spaces like when cards are being crossfired. A single 120mm Noctua fan for me was more effective than any 230mm side fan I tried on my HAF.
 
doyll said:
Having more static pressure in "reserve" gives us peace of mind in knowing we will have good airflow with or without resistance.

Here's another example using cfm and mm H2O:
  • If we have an 80cfm / 0.8mm H2O and an 80cfm / 2.5mm H2O
  • If we have 0.0mm H2O resistance both fans will be flowing about 80cfm.
  • If we have 0.2mm H2O resistance the 0.8mm H2O fan will flow about 62cfm and the 2.5mm H2O fan will be flowing 77cfm
  • If we have 0.5mm H2O resistance the 0.8mm H2O fan will flow about 30cfm and 2.5mm H2O fan will flow about 70cfm.
  • If we have 0.8mm H2O resistance the 0.8mm H2O fan will not flow any air and the 2.5mm H2O fan will still be flowing 60cfm.
Keep in mind this is using a linear graph of mm H2O : cfm and in reality this is not what the graph is, but it would be similar.. probably less than +/- 4cfm, and hopefully it explains why I consider having more static pressure as "reserve" performance.
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You completely missed what I said. Or I should make something more clear.

At the same RPM (and noise level), you either give up CFM for static pressure, or static pressure for CFM. You don't get both without raising RPMs. That's why it is important to choose the fan based on what you will be using the fan for.
 
Tsumi said:
You completely missed what I said. Or I should make something more clear.

At the same RPM (and noise level), you either give up CFM for static pressure, or static pressure for CFM. You don't get both without raising RPMs. That's why it is important to choose the fan based on what you will be using the fan for.
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I think the point is there are very very few cases in which simply more CFM with low static pressure will benefit a typical computer case compared to the many fans which have good CFM, good pressure and are relatively quiet.

Run a dust filter? Static pressure fan
Heatsink? Static pressure fan
Mesh on your case? Static pressure fan
Grill? Static pressure fan
Radiator? Static pressure fan
Narrow spaces between components? Static pressure fan
Crossfire/air cooled? Static pressure fan
Wide open case, with no grills, mesh or other intake obstructions? Air flow fan
 
Tsumi said:
You completely missed what I said. Or I should make something more clear.

At the same RPM (and noise level), you either give up CFM for static pressure, or static pressure for CFM. You don't get both without raising RPMs. That's why it is important to choose the fan based on what you will be using the fan for.
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I think you are missing it.

Yes, we can get two fans to perform at same rpm & noise level with different static pressure ratings (well, with only sight differences). It all depends on number of fan blades and blade design. I'm speaking of "real world" noise where there is resistance causing fan to make more noise as well as grill, filter, etc. making noise. While the fan with higher static pressure rating may be slightly louder in open air test, when the airflow has resistance their noise levels balance out.

My example is of two fans same size, cfm and rpm with different static pressure ratings.
  • The one with 0.8mm H2O rating at 0.8mm H2O stops flowing air, it's flowing 0.0% of its rated cfm.
  • The one with 2.5mm H2O rating at 0.8mm H2O is still flowing 50-60cfm, about 66% of it's 80cfm.
SilverSliver said:
I think the point is there are very very few cases in which simply more CFM with low static pressure will benefit a typical computer case compared to the many fans which have good CFM, good pressure and are relatively quiet.

Run a dust filter? Static pressure fan
Heatsink? Static pressure fan
Mesh on your case? Static pressure fan
Grill? Static pressure fan
Radiator? Static pressure fan
Narrow spaces between components? Static pressure fan
Crossfire/air cooled? Static pressure fan
Wide open case, with no grills, mesh or other intake obstructions? Air flow fan
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Indeed. And I don't see having more mm H2O / static pressure rating than needed in "reserve" as a problem.. but not having enough which results is less or no airflow is a BIG problem.

A good example of this all working in harmony is a case like Define R4 with stock R2 fans making as much or more noise with much less airflow than when they are replaced with a higher static pressure fan like Noctua or Thermalright.

We could even go a step farther and use PWM fans controlled by motherboard / GPU PWM fan header PWM signal with PSU power the case fans will change rpm / airflow as CPU / GPU load and fan rpm / airflow speed / demand changes. Everything is virtually silent when system is not working hard and still quiet at full load.
 
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SilverSliver said:
Considering most people don't like 230mm fans much, I doubt it. 230mm fans have great CFM to noise ratings, but terrible static pressures. With how close they are to GPU's they simply don't seem to have the pressure to overcome the tight spaces like when cards are being crossfired. A single 120mm Noctua fan for me was more effective than any 230mm side fan I tried on my HAF.
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you have enlightened me to this aspect,


/respect
 
Gentlemen, I need two fans for my Zalman 320 and I'm thinking of getting two Noctua NF-F12 PWM Cooling Fans. Will I be satisfied with the noise levels? Are there better choices?
 
Hulk said:
Gentlemen, I need two fans for my Zalman 320 and I'm thinking of getting two Noctua NF-F12 PWM Cooling Fans. Will I be satisfied with the noise levels? Are there better choices?
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Noctua are nice fans, but expensive. If it was for a case fan that was running all the time, they non-pwm version ones are a solid choice. For PWM fans, Akasa Viper's are cheap and have good static pressure, as do Arctic F12's.
 
SilverSliver said:
I think the point is there are very very few cases in which simply more CFM with low static pressure will benefit a typical computer case compared to the many fans which have good CFM, good pressure and are relatively quiet.

Run a dust filter? Static pressure fan
Heatsink? Static pressure fan
Mesh on your case? Static pressure fan
Grill? Static pressure fan
Radiator? Static pressure fan
Narrow spaces between components? Static pressure fan
Crossfire/air cooled? Static pressure fan
Wide open case, with no grills, mesh or other intake obstructions? Air flow fan
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Add one more to that list...
Exhausting air out of a case with no radiator/heatsink directly in front of fan? Air flow fan
 
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