Fan Cooled radiator, stoping resonation.

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Ragnarok
Posts: 23
Joined: Sat Jun 28, 2003 3:11 pm

Fan Cooled radiator, stoping resonation.

Post by Ragnarok » Wed Jul 08, 2009 11:54 am

Just got a watercooling kit with a 3x 360 (XSPC RS360) radiator and I already have a load of fans to try, to get the most out of my i7 without keeping me awake at night. I'm not expecting silence but the quieter the better as always

I've managed to almost completely dampen the pump, mounting it on foam.

However I never expected the radiator to act as an resonation amplifier for fans that are normally regarded as quiet.

Scythe kaze, thermalright, arctic cooling PWM 12025, fans all resonate quite alot and I want to get the running around 800RPM and they still cause the rad to resonate. it an annoying noise rather than a loud one.

I didn't try the Scythe Gentle typhoon which has higher frequency noise compared to most fans, The other things I could try is a shroud.


Any other Ideas?

nici
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Joined: Thu Dec 16, 2004 8:49 am
Location: Suomi Finland Perkele

Post by nici » Wed Jul 08, 2009 2:57 pm

A shroud is good if you have room for it. Reduces backpressure so you can run the fans slower or have better cooling at the same rpm. might make it easier to decouple the fans too. Plenty of ways to do that in the fans section. I usually use weather stripping and zipties, easy and works well and is secure. Makes a good seal around the fans too. Nachos.

Ragnarok
Posts: 23
Joined: Sat Jun 28, 2003 3:11 pm

Post by Ragnarok » Thu Jul 09, 2009 6:30 am

Ether that or I could build rad box :). fans on 1 side, rad on the other.

ascl
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Location: Sydney, Australia

Post by ascl » Thu Jul 09, 2009 5:14 pm

Martin over at XS did some testing on the optimal shroud size... and you don't want more than about 30mm or it actually reduces the effectiveness of the fan. So if you build a rad box, make sure you are careful about the distance from fan -> rad.

Vidicio
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Location: Finland

Post by Vidicio » Sun Jul 19, 2009 12:25 pm

ascl wrote:Martin over at XS did some testing on the optimal shroud size... and you don't want more than about 30mm or it actually reduces the effectiveness of the fan. So if you build a rad box, make sure you are careful about the distance from fan -> rad.
Optimal shroud depth is not a fixed number. It may depend on push/pull, fan size, fan speed, etc.

In my radiator mount (viewtopic.php?t=54589), I used 55 mm distance, which seems to work fine (no, I didn't experiment with many distances) with slow RPM Noctuas pulling the air. Slow RPM and pulling rather than pushing is anyway good idea when you need silence. Extra heat radiation surface seemed also good idea for reduced airflow resistance.

My radiator doesn't keep any resonation noise. Possibly because it is hanging by 5 mm thick elastic cords with the fans.

ascl
Posts: 279
Joined: Tue May 05, 2009 1:15 am
Location: Sydney, Australia

Post by ascl » Sun Jul 19, 2009 4:06 pm

You are right, push vs pull makes a difference, and possibly the fan thickness.

The link is here, its a worthwhile read:
http://martinsliquidlab.i4memory.com/Ra ... eview.html

Ideally you should test it yourself, as your exact parameters may be different... but I think as a general rule, pull for low-med speed fans, and push for high speed fans, and a shroud of 30-50mm is a good starting point.

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