Need some help with Airflow

[Dkozak]

So I'm probably going to upgrade to an NZXT H440 and I've designed an airflow scheme but I'm not sure which fans to use where.

 

The scheme: 

 

• I know the Cooler Master Sickleflows aren't the best fans but I already have them and I'm happy with them
• I also know no one likes the CM Seidon 120V because rev 1 sucked but rev 2 keeps my 4790K cool @ 24-26° C which is good enough for me.
• the included NZXT fans are the FN V2 fans
• The arrows indicate the intake and outtake

 

Now what I want from you guys: 

 

What is your opinion on this setup?

What would you change and why?

 

Note:  as said before the Sickleflows aren't the best but I have them so I'm not going to buy other fans.

[don_svetlio]

3 intakes front, 3 exhaust - 1 back, 2 top. you need to balance air pressure

[Patrick Bateman]

looks decent i guess

[JoshPC]

Well if your going to be using a radiator, use SP (static pressure fans) on the radiator. But Airflow is optimised for uses. Linus has some videos going more in depth about what fans are used for what situations.

[Patrick Bateman]

3 intakes front, 3 exhaust - 1 back, 2 top. you need to balance air pressure

well thats what it is look at it. and then the fan on the end of the top near the front of the case could be intake ?

[Dkozak]

well thats what it is look at it. and then the fan on the end of the top near the front of the case could be intake ?

So the first two at the top exhaust and the last one intake? Isn't the air going straight to the 140 exhaust at the back then?

 

Well if your going to be using a radiator, use SP (static pressure fans) on the radiator. But Airflow is optimised for uses. Linus has some videos going more in depth about what fans are used for what situations.

Static pressure as push or pull? I know the Sickleflows are somewhat SP

[JoshPC]

So the first two at the top exhaust and the last one intake? Isn't the air going straight to the 140 exhaust at the back then?

 

Static pressure as push or pull? I know the Sickleflows are somewhat SP

Just on radiators

[Dkozak]

Just on radiators

Yeah sorry I was a bit unclear there. I ment Push or pull on the rad

 

Eg:

- Sickleflow | Rad | NZXT included | front

- Sickleflow | Rad | Sickleflow | front

- NZXT included | Rad | Sickleflow | front

[petem]

So I'm probably going to upgrade to an NZXT H440 and I've designed an airflow scheme but I'm not sure which fans to use where.

 

The scheme: 

 

<pic removed for clarity>

• I know the Cooler Master Sickleflows aren't the best fans but I already have them and I'm happy with them
• I also know no one likes the CM Seidon 120V because rev 1 sucked but rev 2 keeps my 4790K cool @ 24-26° C which is good enough for me.
• the included NZXT fans are the FN V2 fans
• The arrows indicate the intake and outtake

 

Now what I want from you guys: 

 

What is your opinion on this setup?

What would you change and why?

 

Note:  as said before the Sickleflows aren't the best but I have them so I'm not going to buy other fans.

 

This question is asked so often, we should just make a sticky and direct everyone there, lol.

 

Fan basics: the whole idea for case fans is to move air efficiently across components that need cooling.  This is usually done by having intake fans on the front/bottom, and exhaust fans on the back/top.

 

For decent air flow, I prefer positive pressure (i.e. higher pressure in the case than outside), such that the intake total CFM is about 5-10% higher than the exhaust CFM.  Assuming the fans are similar, in that they move the same amounts of air proportional to their size, you can simplify things by just comparing the relative surface areas of the intake fans to that of the exhaust fans, without having to account for variable speeds, actual fan diameters, blade efficiencies, and whatnot.  To do that, just square the fans size (in cm, no point in complicating the math unnecessarily), and add them up for both types (exhaust and intake).

 

If some of the exhaust fans are pushing air through a radiator or some other obstruction, you can probably have them about 1:1, since the radiator exhaust fans won't be as efficient as the relatively unobstructed intakes.

 

Quick Example: 3 x 120mm and 1 x 140mm intake fans = 3 * (12*12) + (14*14) = 628

                         4 x 120mm  exhaust = 576, for about 9% more intake air.

 

If you are going to actually use a fan controller or have significantly different rated fans, then the math gets more complicated and you'll need to know the fan specs (how much CFM at what speeds) to figure out the actual exhaust:intake ratio.

 

In your case (pardon the pun ), you don't have nearly enough intake fans to keep positive pressure in the case.  Too much exhaust will cause air to be drawn in around the cracks or even right next to the exhaust fans, which usually causes eddying in the case and inefficient airflow across the motherboard / components.

 

Treating the CPU cooler as a normal 120, the 3 120s in and 3 120s out would be a wash, and the extra rear 140 exhaust would create a lot of negative pressure in the case.  And with the top front fan for a CPU water cooler, that's even worse, since it won't supply as much air as a free-flowing fan.

 

Also, radiator coolers are not cut and dried.  2 schools of thought:

• run the coolest air over the radiator- which means your are pushing warm air into the case  :huh: or
• exhaust the warmed air out, which means you are using the warmer case air to "cool" your radiator, also  :huh:

I like a simple adjustment that addresses both issues:

 

Use the rear 140 as an intake and put the cpu radiator/fan right above it to exhaust the heat out.  That ensures cool air to the radiator and also exhausts the warm air directly out of the case. Win win.

 

Then use 2 120's on the front bottom positions, and 2 more for the other 2 top positions, and you should be good to go 

 

Hope this helps!

 

- Pete