Case Fan Offsets for Increased Flow?

SH4RKY

SH4RKY

SH4RKY

Associate
Joined
28 Aug 2004
Posts
766
Location
b'ham
Out of interest.... I've seen a few things about air pressure of fans etc, and was curious about placement of case fans for optimal airflow and reduced noise...


My thoughts are:

Having input fans at the front of the case pushed up against dust meshes and grills etc creates additional noise through turbulence and air being forced over the extra surfaces and, from the very little I understand about it, a low pressure fan may have trouble sucking air through these materials... ?

Therefore would it be better to offset the fan back into the case by an inch or 2 to allow air to be freely pulled through the fan (air would partly be from inside the case, but mostly from the outside) and just allow a natural suction of air through the dust meshes that would be created by the pressure of the fan a short way inside.

:confused:


I've done some very rudimentary tests and having a mesh in front of a fan does appear to increase noise and cuts the air flow more than if i hold the fan a short way away from the mesh... but i havent done any temp monitoring or actually fixed the fan in position to test.

Just curious about what other people have found and any info or tips about air pressure etc.


I have a p182 case, thats already pretty quiet, but am thinking about replacing the 120 fan I have suspended in the drive bay with a 140 fan and replacing some of the tricools with a higher air flow but quieter option. (Noctua NF-S12B FLX, maybe sharkoon golfballs, or asaka ambers).
 
Also... i assume the same applies on the rear... anyone cut away the finger protective grid at the rear of the case for improved air flow?? Would think a fan protector could be fitted to increase H&S... (smother and smaller profile than standard case stuff.)


err... also, i think this is in the wrong forum, i saw cooling and chucked it in here, but i think it belongs in the case forum. Can a friendly mod chuck it over there please?
 
Good a place as any.

The rear example I've done and the chrome x guards (or no guard) allow much higher air flow that the intergral punched metal case grills.

As to dust filters and stand offs - no personal testing but anything in the way will affect flow. High speed fan will be more affected that low speed. and low pressure fans affected more the high static pressure ones
 
Ive cut the the fan grid at the back of the PC case on my older one, it had quite small holes so cutting them did make a reasonable difference to airflow and noise.

But for example my current case is an antec akasa and its grid fan protectors are pretty decent so I havent cut those.

Its nice to sit and optimise airflow etc but in reality the difference is negligible at best.

Once thing though is I always try to use as large fans as possible as then I can lower the RPM and still maintain a decent level of airflow. Lower RPM means less noise. I also find the larger the fan, the more low frequency the noise it produces and even at a highish RPM its still acceptable.
 
Shrouds! Yep, these are good.

I'm going to cut the grill out of my case when I get around to it, but haven't bothered yet
 
You might just try re-drilling the holes in your grill to a bigger size. I mean it may be a minute difference on each hole, but all together you'd lose some resistance. I think I read that somewhere, lol.
 
A 140mm fan doesnt fit in the 3 drive bays under the DVD drive... which is a shame as it fits in beautifully width-wise. An option i need to play with is moving the DVD to the bottom bay and checking if the small gap at the top of the top bay is enough to squeeze a 140 in.

If not, ill have to create a string cradle/hammock to suspend a 120 fan within the spare 3 drive bays.

Also, I read that for best cooling/airflow its important to get more air going into the case, rather than the other way round. Helps to give direction and source to the air rather than just letting it be sucked in through open gaps. Also helps reduce dust as the air will be coming in through dust filters etc rather than the gaps.

Struggling to think about paying 18 quid for a noctua when for 4 quid you can get a yate loon and run it at 7v... :)

Oh, and making the PC case quiet is pretty irrelevant when the loudest thing in there is actually the GPU... haha. Might think about replacing the stock fan on the GTX260 if there is a cooler and quieter option around. Read that EVGA dont mind you replacing fans etc, just as long as if the card has to go back you put in back the way it was when it was bought...
 
SH4RKY said:
A 140mm fan doesnt fit in the 3 drive bays under the DVD drive... which is a shame as it fits in beautifully width-wise. An option i need to play with is moving the DVD to the bottom bay and checking if the small gap at the top of the top bay is enough to squeeze a 140 in.

If not, ill have to create a string cradle/hammock to suspend a 120 fan within the spare 3 drive bays.
Click to expand...
Could get one of these when they are back in stock.. look nice too..
http://www.overclockers.co.uk/showproduct.php?prodid=SY-000-SY&groupid=701&catid=57&subcat=399
 
Last edited:
Yeah, Ive been meaning to grab one of those for quite a while. Was going to until i started thinking about offsetting fans into the drive bay.

I already have some mesh shaped to fit in the space from my old pc. I made my own bracket for a 120fan though and mounted it much the same way as that scythe (little less well finished but performed admirably. This time im thinking a string cradle will help reduce vibration/resonance and will help me off set the fan away from the mesh.
 
You must log in or register to reply here.
Back
Top Bottom