COOLING: How much CFM do I need?

[Evinety]

My parts are listed here: http://au.pcpartpicker.com/user/Fvp/saved/JjwCmG

I will have a Corsair H80i so the CPU will not need to be cooled further. The case will be the Corsair 750D.

Everything will be overclocked.

What would you suggest is a good CFM of airflow?

Also, i've been thinking, would it be better to have more fans that run at less RPM's or less fans that run at more RPM's?

Cheers!

 

[bootcher]

Unless you don't mind your computer booting up sounding like the launching of a spaceship, I personally like less fans, also at less rpm. Get big and quiet fans. Airflow is always cold air intake from bottom front, hot air exhaust from top rear. Since your cpu cooler already will be using one spot, you only need 1 extra fan you can mount on top if you want. Since your cpu is cooled and your videocard blows hot air out it's back already, I don't think you will need more fans.

 

[synphul]

More fans at less rpm's will move the same air (provided they don't conflict, aka blowing 90 degrees from each other) and be quieter. That's why fans have continually grown larger - 80mm, then 92, 120, 140, even some large specialty fans on the side of a case at 210-240mm. They don't have to spin near as fast to move the air and creates less noise.

I don't know that adding up the cfm of the fans equates to actual airflow movement in the case. If the case is x amount of cubic inches, I'm sure there's formulas that try to figure out the cfm needed to exchange the air x amount of times per minute but you have to factor in airflow dynamics in the case, obstructions, static pressure etc etc to come to all that conclusion.

Many 120mm fans available will move around 75-85cfm each and still at low noise levels.

Is the h80i in place of the rear exhaust fan or mounted to the top? The case already comes with 2 140mm fans up front and one 140mm for the rear exhaust. I'd start with those and maybe add another 140 in the top (assuming your h80i is also on top). At some point you're going to reach a point of diminishing returns on fans.

 

[Evinety]

Thanks for the answers. I have decided to remove the stock fans and utilise every available millimeter for the following:

- Corsair H80i (rear exhaust)
- 3x Corsair Air Series AF120 120mm RED (top exhaust)
- 2x Corsair Air Series AF120 140mm RED (front intake)
- 2x Corsair Air Series AF120 120mm RED (bottom intake)

These fans are the 'quiet' versions of their series. I'll run them on their lowest possible voltage. It should provide excellent airflow, good temperatures and a great LED-light show.

I've seen a few popular YouTube channels utilise this method and the noise level was very quiet (a coin drop was deafening in comparison).

 

[synphul]

You should definitely get some air movement. There's always a tradeoff between fan count, fan speed, air movement and noise. If you're looking to control them directly, you may want to check out a fan controller that fits into a 5.25 bay. Let the motherboard control the cpu cooler and control the other case fans with a rheostat style controller. Sometimes if a fan is audible it doesn't have to be lowered all the way to its' lowest speed. Just dropping speed a little off the upper end makes a huge difference. Most of my fans I can turn up to around 70% (guesstimate from the knob location off to full) before I can hear them so as to find a balance between low noise and good airflow.

 

[Evinety]

You should definitely get some air movement. There's always a tradeoff between fan count, fan speed, air movement and noise. If you're looking to control them directly, you may want to check out a fan controller that fits into a 5.25 bay. Let the motherboard control the cpu cooler and control the other case fans with a rheostat style controller. Sometimes if a fan is audible it doesn't have to be lowered all the way to its' lowest speed. Just dropping speed a little off the upper end makes a huge difference. Most of my fans I can turn up to around 70% (guesstimate from the knob location off to full) before I can hear them so as to find a balance between low noise and good airflow.

The Australian PCPartPicker is quite limited in fan controller options it seems. Can you use 3-pin fans on a fan controller made for 4-pin?

 

[chenw]

There should be plenty of adapters that can change a 3 pin from the fan to 4 pin on the fan controller. Not sure if all fans include them, but the fans I was looking at (Mainly Enermax LED fans) did have them.