Fannage and air intake

[Teq]

Just a quick question...

I see lots of people adding multiple exhaust and intake fans to their computers. But I have to wonder how much people are doing to increase the actual airflow capacity of the case itself...

I've worked with quite a few cases in my day, by and large the intakes under the fronts of the cases, and on the side panels seldom amount to the same area as the fan mounts in the back. Obviously 31 fans aren't going to help your case if they can't get air to push...

So how many people actually do case-mods to increase the case's airflow, rather than just sticking in more fans?



<b>(</b>It ain't better if it don't work.<b>)</b>

 

[Guest]

me.

I also have convinced myself that by reducing turbulence in front and behind fans, the result will be quieter operation.

To increase fan efficiency further I also glue those little plastic easter egg halves to the front of the fan to eliminate the dead spot in front of the flat fan hub surface. Ducting is another trick I use.

You'll find that many here have even gone so far as buying those wrapped up ribbon cables to increase airflow. Something I have not done.

 

[Teq]

Hmmm... interesting... have to experiment with the plastic cone thing...

The reason I asked is that I just did a case mod for a friend where I cut a large rectangular opening into the bottom (underneath, out of sight) of the front cover of his case. This increased the area of the case's various air intakes by about 200% I was surprised to see a 6c degree reduction in case temperature, with only one case fan running.

Things got a lot quieter too...

I was hoping to find out if this was a fluke or something I sould consider as a regular mod to be offered as part of my work...


<b>(</b>It ain't better if it don't work.<b>)</b>

 

[lhgpoobaa]

Well ive doen a bit... mostly ghetto mind.
My first case was an omni steel POS.
It was a damn furnace cauz it only had 2 fanholes, one front one back, and both were only really that punched steel fanhole. and that DOES NOT let out much air... less than 50% of the fans actual flow i estimate.
Whats worse the front fanhole was also enshrouded by the front plastic bedsel with ah heck all airholes, effectivly reducing the airflow too zero.

So first off i got metal cutters and removed the punched grills. alot better! after a while i stopped upsing the front fan as the plastic front made it basically useless.

Even with just the rear fan running there was significant pressure problems (air still couldnt get in) so i removed one of the floppy drive bay covers. (also cooling the hard drive below better)

Then last november i just ditched the case. Got a nice nice NICE atlas case that comes with 6 fanholes... i only run 3 of the 6 fans and still get fantastic ventilation. all 3 fans are exhaust ones... they draw thro the empty fanholes quite well.

<b>"If spam wasn't totally bogus, Hotmail users would be well-endowed, slim people with hair who make big money working at home and having great sex provoked by free porn and herbal Viagra.</b>

 

[lhgpoobaa]

and yes. plastic coes do work... also for those fan adaptors e.g. 80mm to 120mm to reduce turbulence. also good for removing the fan deadspot that just happens to be located abve the hottest part of the heatsink.

<b>"If spam wasn't totally bogus, Hotmail users would be well-endowed, slim people with hair who make big money working at home and having great sex provoked by free porn and herbal Viagra.</b>

 

[NE_Corridor]

I was wondering if the pastic cones work equally well for fans that suck in air as well as those for pushing air out?

Call me Caine.

 

[NE_Corridor]

I was wondering if the pastic cones work equally well for fans that suck in air as well as those for pushing air out? Seems like a good idea.

Call me Caine.

 

[Guest]

If you look at the front of most jet engines, ie at the intake, you will see egg shaped nubs in the center. I assume that the change in air velocity between jet and PC case fan apps isn't changing the flow patterns that much, then again my brain is lacking for accuracy in this type of simulation, as I know nearly nothing about the subject.

I think copying Boeing is about as good as I can do. They are the ones with wind chambers and billion dollar R&D budgets.

The qestion has come up in my mind about which curve would be best, but again the little easter egg halves look almost identical to the things on the fronts of the jet engines, and I just don't have the expertise/tools to take it any further.

 

[Teq]

I tried this with half a ping-pong ball, mounted with crazy glue... didn't make much difference to the sound, but there did seem to be an increase in airflow... Anyone know where I can get black ping-pong balls?

Damn... the things you learn when you least expect it



<b>(</b>It ain't better if it don't work.<b>)</b>

 

[lhgpoobaa]

yesss... well the fans are one and the same, it just depends what side you put the cone on.
Its easy to attach them on the 'air out' side as that is where the fixed fan hub is. just glue them on and away you go.

the otherside however is the spinning fan center, so you gotta make sure the cone is perfectly symmetrical, otherwise it will be unbalanced and vibrate badly.
The fan rim will also hae to be deeper to accomodate the cone too.

<b>"If spam wasn't totally bogus, Hotmail users would be well-endowed, slim people with hair who make big money working at home and having great sex provoked by free porn and herbal Viagra.</b>

 

[Guest]

Yeah, this place is great for that. Every now and then someone will drop a golden easter egg, and you just have to be there to catch it.

I won't lay claim to the idea. I just try to remember, and regurgitate the good ones when I can.

Edit: -1 for punctuation

<P ID="edit"><FONT SIZE=-1><EM>Edited by knewton on 03/05/03 05:22 PM.</EM></FONT></P>

 

[jihiggs]

get some spray paint, geeez

my computer is so fast, it completes an endless loop in less than 4 seconds!

 

[zed201]

go to a hobby shop and look at the modle airplane prop spiners they should have one to fit

 

[samtesla]

Keep in mind that since noone rewrote the laws of thermodynamics recently , you may mess things up by opening a large hole in your case. My main system's case (Elan Vital T-10) runs several degres WARMER with the side cover OFF than with it on .

This was true when the case housed an Asus P2B and a P2-350, and is true now with a 2.4ghz P4 on a P4S533.

The only 'mod' will be adding some sound dampening material, not that it matters much... The computer room is very noisy here at home.

ST

 

[phsstpok]

All I did was cut out the punched holes front and back which gave me 80mm openings. The increased airflow allowed me to dump the two 40 CFM case fans for quieter 32 CFM front and 26 CFM back fans. (I think those were the values). The PSU fan picks up the remaining CFMs.

The case fascia does not seem to be a problem as air comes in from a large opening at the bottom of the plastic.

I played with just one case fan but I didn't like my results.

<b>99% is great, unless you are talking about system stability</b>

 

[lhgpoobaa]

i did that with my old craptacular case to get better airflow. problem was the front bedsel was in the way and allways hampered flow. in the end i was just running one medium rear casefan. adding a front one just incresed NOISE.

with my current case its got room for 6 80mm fans, but i only run with 3, all pushing air out.

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[phsstpok]

Bezel is not a problem for me but I only have room for one fan front and one fan rear. I tried a single 40 cfm fan in each location but didn't like the results so I went to two 40 cfm fans.

Recently I swapped a 2.1 Ghz Tbred B for a 1.5 Ghz Tbird. Ever since then cooling has been relatively easy.

I dumped my old heatsink with 36 CFM fan for one with just 22 cfm and as I mentioned the 40 cfm case fans have been replaced as well. The net result, no substantial change in CPU temps. Huge difference in sound, though.

Now my K6-2 system is the loudest one in the room. The Tbred system can still be heard but it kind of just purrs.

<b>99% is great, unless you are talking about system stability</b><P ID="edit"><FONT SIZE=-1><EM>Edited by phsstpok on 03/27/03 09:30 PM.</EM></FONT></P>