Just a quick question: the wind noise associated with stock chassis grills - is that from the intake fans or from exhaust fans (ie. wind blowing out of grill or being sucked in through the grill)?

I am looking into reducing fan speeds (either 5V/7V mod or fan controller) as I do not want to cut my chassis, and wondering which would be more effective to slow down.

Cheers,
X

Both, but mostly from exhaust.
Keep in mind that the fan grills negative impact on the airflow will be of more concern with a slow running fan.

i also wondering the exact same thing

i use noctua 120 pf fan on my norco 120mm fan blade and was expecting truly silent operation. instead i heard a noticeable woosh sound. the fan grill is on the intake. by switching the grill to be on the outtake/exhaust, does the woosh sound reduce? if it only takes 5 minutes to swap, i would do it no problem. thing is it takes hours to do so.

from what i read, it seems that the grill is better to be at outtake/exhaust. but i need confirmation(like scientific facts).

thanks.

I have these experiences:

PSU with SlipStream 1200rpm undervolted to approx 4-500 rpm. It pulled air through air vents on the bottom of the NZXT H2. Really annoying noise which disappeared when I flipped over the PSU which would then take air in from inside the case, i.e. with no air restriction.

Same fan setup as above as exhaust in NZXT H2. I can easily feel that much heat is trapped by the honeycomb metal in the rear fan position.

With a slow running ran (low CFM) you may be concerned about losing CFM, but a grill will have less impact on CFM. The impact of the grill multiplies exponentially as the speed of the air increases. If all you have is a 300rpm fan giving a slight drift to the air, the fan grill is not likely to have much of an impact, if at all.

The worst is actually intake, at least when I tested. I creates some odd backdraft that you can really notice, even at lower voltage (3,5V) with all the elite fans.

I ended up not using a side in take but using the slot in the bottom of my case (Fractal 3000). That solved it.

If the grill is too close to the intake side of the fan it will make a lot of noise.

Without grills, you can often slow the fan even more, and still get decent temperatures.