Noise Reduction On The Cheap

[kazaa2002]

Skillian, this noise reduction is not cheap, however
when this gets into the mainstream, it might be worth a look
for your next pet project

http://www.pcmag.com/article2/0,1759,1531416,00.asp

This Voodoopc Rage f:50 has no fans and no water cooling unit
the reviewer says it is very quiet but it is also very heavy.

[Skillian]

20 decibels would be very good, and that case looks proper smart.

I don't much like the idea of having to join VoodooPC's Upgrade Assistance Program if I want to upgrade the graphics card though

Fact is, when BTX cases come out noise reduction will be alot easier as it will seriously reduce the need for case fans and stuff. I'd wait for that before buying a quiet ATX case.

[clocker]

Originally posted by james_bond_rulez@7 April 2004 - 13:19


Why not use a water cooling solution? it's quiet and doesn't require fans...well except for the psu

Water cooling doesn't require fans?

With the exception of the Zalman Reserator and the Innovatec rads, most H2O rigs that I've seen use large, high flow fans.

[tesco]

Originally posted by clocker+7 April 2004 - 21:59--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (clocker @ 7 April 2004 - 21:59)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-james_bond_rulez@7 April 2004 - 13:19


Why not use a water cooling solution? it&#39;s quiet and doesn&#39;t require fans...well except for the psu&nbsp;

Water cooling doesn&#39;t require fans?

With the exception of the Zalman Reserator and the Innovatec rads, most H2O rigs that I&#39;ve seen use large, high flow fans. [/b][/quote]
I knew you would post disagreeing with that post...lol

anyway i wanna add that just because youve got watercooling doesnt mean that their wont still be heat in your case. there are many other heat producing things in a computer, such as teh northbridge, souhtbridge, harddrive, videocard, optical drives and they all need sufficient airflow too. then where is all the heat from your radiator going, inside your case? all of that air also has to be removed from your case, so it ends up being probably just as loud, or atleast pretty close.

[FlyingDutchman]

Hi Scillian.

As said before, first you need a plan, then come up with a design, then execution.

The Plan:

Given the restrictions (resonable cost, should look good) it seems smart to:
* show as little as possible the tinkering done to the PC,
* try to establish the wished air-flow,
* reduce air-resistance so low revving fans can cope with their cooling task.

*as an extra I&#39;ll throw in a duct. You might consider using one.

Now this charts shows the problem we&#39;re facing:
Image Resized
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[img]http://www.bijlard.demon.nl/Cooling/p-rpm2.gif' width='200' height='120' border='0' alt='click for full size view'>
Below 500 rpm no fan is capable to produce a difference in pressure, and thus can move a reasonable amount of air. Higher revving fans can move air but above 2000 rpm their noise production climbs even faster.
For a given rpm small fans produce less noise than lager ones, but large fans move a greater volume.

From the chart you can see that in the rpm range we&#39;re aiming at (800 - 2000 rpm) fans produce a pressure of some .5 to 1.5 mm water pressure (1/32 - 1/16 " water). This is hardly any pressure at all, so air resistance should really be minimized.
Here is one example how you can lower air-resistance:
Image Resized
Image Resized
[img]http://www.bijlard.demon.nl/Cooling/Bend%20Spokes.jpg' width='200' height='120' border='0' alt='click for full size view'>
Using needle nose pliers you can twist the spokes on the PSU&#39;s air-intake.
The picture was taken to show the difference, but the bottom row must be treated as well of course.

AMD advices to strive for an airflow like this, using a PSU with a bottom-intake.
Image Resized
Image Resized
[img]http://www.bijlard.demon.nl/Cooling/AMD-2.gif' width='200' height='120' border='0' alt='click for full size view'>
You have a PSU with front-intake, and a restricted front intake on your case, so let&#39;s strive for an airflow like this:
Image Resized
Image Resized
[img]http://www.bijlard.demon.nl/Cooling/Bottom_to_top.gif' width='200' height='120' border='0' alt='click for full size view'>
This is the intended airflow so all the holes above the level of the AGP graphics card should be closed or fitted with an expelling fan. Especially these holes in the pic below have to be closed. The ones on the other side too of course.


Here a few more examples of holes that need to be closed:

and


Now mount 2 slow revving case fans in the rear.
Mount 1 slow revving case fan in the top
Mount a slow revving 120 mm fan in the front (blowing air in)
If you want, keep the LED-fan in the side, but disable the fan and close the hole with tape or plastic film.
When you haven’t enough air coming in, open up one or slot covers as indicated by the arrows here in the rear:


These changes should quiet down your rig considerably, though you might need to change you PSU-fan for a less potent kind.

Continued in next post as the forum said:
"Sorry, but you have posted more images than you are allowed to"

[FlyingDutchman]

Continued from previous post:

Now, some drawings of a home made duct, guiding polluted air to the rear-case fans.
These pictures should explain it better than I can in words.


Image Resized
[img]http://www.bijlard.demon.nl/Cooling/Hood2.gif' width='200' height='120' border='0' alt='click for full size view'>



The idea is (depending on suitability of the CPU-heatsink) you flip the fan on the heatsink, so it sucks air through the heatsink. Then the hot air is caught in the hood and expelled from the case without a chance of polluting the case with its heat.
This results in the PSU taking in cooler air so it can get by with a weaker fan.


Think about it, and feel free to ask when you&#39;re not convinced.

Regards.

[FlyingDutchman]

Originally posted by Skillian@7 April 2004 - 20:33
Is that what I should ask for, sheetmetal nibblers? I don&#39;t want the hardware atore guy to laugh at me

I was also wondering if that airflow was strong enough. Does anyone know what the CFM of a stock AMD fan is (that&#39;s what I&#39;m using currently using)?

Is it fair to compare the air flow of a 60mm to an 80mm? i.e. if the airflow of the AMD fan is 30 CFM, should I expect the same performance from a 30 CFM 80mm fan?

nibbler

At the same air-flow (volume) a smaller fan produces a higher pressure.

Air-flow is roughly in line with: (size ^ 2) * thickness * rpm.

So, as the 80 mm fan is both larger AND thicker than the 60 mm fan, it is almost certain to displace a much higher volume.

[FlyingDutchman]

Originally posted by Skillian@7 April 2004 - 19:48
OK, the quiet fans I will have a look for - I did find these Zalman Stealth Fans - at 20dBA and a slightly higher airflow than the Vantecs they sound pretty good. I&#39;m thinking one for the PSU and one for the CPU.

I&#39;ve had a look around and I don&#39;t have any of the tools needed for cutting the grills or a hole in the top of my case. In theory I could buy them but I am trying to keep the cost down. What exactly would I need. Tin snips to cut the grill and some sort of sanding tool to neaten it up I guess. Those wouldn&#39;t suffice to cut a hole in the top though, as I would be cutting through sheer metal. Perhaps I could perform the easier modifications now and look at doing that later, when I have a bit more money and I can see clearer what needs further work as regards noise and cooling.

Remember my goal here is noise reduction, so I am wary of adding more fans, though I understand the concept that if the cooling is more efficient, less power would be needed to the fans, thus reducing the noise.

Do you think I should try reversing the exhaust fans even if I don&#39;t have a blowhole? I suppose that&#39;s something I could try and see for myself, I&#39;ll have a go tonight.

The fans at the dutch shop I named (link provided) are cheaper and absolutely the best.

Here a nibbler, albeit in the USA.

You are right, generally speaking, you should try to do with the least amount of fans (I have only 3 myself).

But, you said it had to look good. That makes it much more difficult in a case with a window.

[james_bond_rulez]

i got a headache....

[tesco]

Originally posted by james_bond_rulez@8 April 2004 - 21:06
i got a headache....

flying dutchman, it looks like you really know your physics...