HAF 922 fan setup

[Razor505]

Hi, I want to have the best airflow at the same time lesser dust build up, I heard if you have more intake than exhaust it makes a positive air pressure in the case. Here is a picture of my fan setup:

My CPU cooler is a Noctua NH-D14 which is taking air from the front and blowing it to the back.

 

[AddRAM]

My belief is, any fan drawing air in should have a dust filter, the fan up top should be exhausting air, not bringing it in.

 

[linnemeyerhere]

Plus one on the top fan extracting warm case air. No harm with experimentation !

 

[Razor505]

with the top fan as an intake the front 200mm does not take in dust but temps do go up a bit.

 

[madcratebuilder]

I use the Demiflex filter kit on my 922, all fans are intake with exception of the rear fan. It's a push/pull with a 120x1 radiator. Combination of filters and positive case pressure keeps interior dust to a absolute minimum.

I'll be changing the rad to a 120X2 on top and it well be exhaust in a push/pull configuration, that's the plan and subject to change.. The rear fan will be intake in order to maintain positive case pressure. My interior case temps run 1-3C above room temp unless I'm cranking the two 7950's.

 

[N00berG00ber]

Front and bottom ones should be intake, and top and rear exhaust

 

[GeneO]

I have the top fan in my case pulling cool air directly into the intake of the CPU heatsink. It works well. but my top fan is directly over the intake of my CPU heatsink. Yours looks like it may be over the center of the Noctua, so may not be as effective.

With all of the intakes, you should have good positive pressure and I think you don't even need a fan in the back, it may restrict the airflow out. Try letting the Noctua blow it out the hole. Experiment around a little. Maybe an intake on the bottom as well (to ensure positive pressure).

 

[Lordbob75]

Heat rises!

The front and bottom fans should be intakes, with the top and rear fans being outtakes.

 

[GeneO]

Heat rises!

The front and bottom fans should be intakes, with the top and rear fans being outtakes.

It doesn't really matter if heat rises when you have air flowing through the case. Convection gets broken up by the flow of air through the case.

I think that maybe historically having fans on top be exhaust fans is because PSU used to be mounted on top, sucking air in from the top of the case and blowing it out the back. Putting an intake fan on top would not be effective in that configuration because it feed the PSU fan.

 

[Lordbob75]

Heat rises!

The front and bottom fans should be intakes, with the top and rear fans being outtakes.

It doesn't really matter if heat rises when you have air flowing through the case. Convection gets broken up by the flow of air through the case.

I think that maybe historically having fans on top be exhaust fans is because PSU used to be mounted on top, sucking air in from the top of the case and blowing it out the back. Putting an intake fan on top would not be effective in that configuration because it feed the PSU fan.

Correct. The main point is that you want good airflow, but that's been the standard for a while. Even if the heat rising thing isn't hugely important, I could definitely see it making at least a small difference.

 

[GeneO]

Heat rises!

The front and bottom fans should be intakes, with the top and rear fans being outtakes.

It doesn't really matter if heat rises when you have air flowing through the case. Convection gets broken up by the flow of air through the case.

I think that maybe historically having fans on top be exhaust fans is because PSU used to be mounted on top, sucking air in from the top of the case and blowing it out the back. Putting an intake fan on top would not be effective in that configuration because it feed the PSU fan.

Correct. The main point is that you want good airflow, but that's been the standard for a while. Even if the heat rising thing isn't hugely important, I could definitely see it making at least a small difference.

I believe it is completely negligable. Hot air rises due to buoyancy (hot air is less dense than cold) and airflow and turbulence mixing hotter and cooler air inside the case will not let any density gradient form, which is necessary for this to happen. You need a static environment for that if you are passively cooling your coputer without fans, venting at the top may be beneficial.