gusangora Posted March 24, 2007 Posted March 24, 2007 I have designed a cabinet and had it custom built, using pine (35mm & 20mm). To improve air flow and cooling, I have attached some 120mm fans to the rear of the cabinet. These are computer case fans, which I have attached to the HTPC power supply. The fans are very quiet (22dBA) but when I attach them to the cabinet, there is an unacceptably loud vibration sound. In fact, the cabinet starts to resonate whenever the fans are held close to the cabinet, without even touching it. Is there a solution for this issue? Steve pic of cabinet here: http://www.dtvforum.info/index.php?showtopic=47882
Craigus Posted March 24, 2007 Posted March 24, 2007 I got the artic cooling fans that attach to the bracket via rubber connectors. I'm still building my cabinet so can't say for sure if there are any vibration issues, but they are VERY quiet. I got one from http://www.pccasegear.com.au/category115_1.htm. Although they should be easy to get elsewhere.
Volunteer Kazz Posted March 24, 2007 Volunteer Posted March 24, 2007 I got the artic cooling fans that attach to the bracket via rubber connectors.I'm still building my cabinet so can't say for sure if there are any vibration issues, but they are VERY quiet. I got one from http://www.pccasegear.com.au/category115_1.htm. Although they should be easy to get elsewhere. I also have the arctic cooling fans and they have absolutely no vibration noise.
???? Posted March 24, 2007 Posted March 24, 2007 Use spongy rubber washers between the fan and the wood. Make sure you still screw the fans in tight, this should get rid of most of the vibration caused by the fans, thereby eliminating the noise. Also make sure the hole you have for the fan allows enough space for the full circumference of the fan to circulate, only overlapping the wood where it needs to for the screws, otherwise the fans will be pulling/pushing on the wood creating the vibration (especially if the back panel is thin ply or the like).
gusangora Posted March 24, 2007 Author Posted March 24, 2007 The back is 15mm pine slats, like seen on the back of many dressers and bookcases. The fans are very quiet when placed on a table, or held by hand. The resonance/vibration sound begins when I get them close to the cabinet, without yet touching the surface. I have tried rubber washers; the holes cut are 120mm and aligned with the fan opening. The fans are CoolerMaster, operate at 1200 rpm and have 'silent" written all over the packaging (22dBA). It's not the fans that are noisy, it's the cabinet reacting to the fans. Curious though that the HTPC is silent, yet has 7 fans and is completely within the cabinet. Thanks for the suggestions, keep them coming.
???? Posted March 24, 2007 Posted March 24, 2007 It's not the fans that are noisy, it's the cabinet reacting to the fans. Curious though that the HTPC is silent, yet has 7 fans and is completely within the cabinet. Pretty much answering your own question then, especially considering that your HTPC has 7 fans and is silent!!!! Structure of your cabinet is causing the problem which should be reasonably easy to locate. Only other thing I would check is that your fans are all blowing the same direction, including those in the HTPC - otherwise they may be workinig against each other causing the noise
ozdoc Posted March 24, 2007 Posted March 24, 2007 Another consideration is to undervolt the fans to 7v or 5v. . I find even the quietest of 120 mm fans too noisy at 12v, and resonance characteristics change at different fan RPMs. Be aware that some fans won't start at 5v. I'm not sure about the advice to screw the fans in tight. Rattle is reduced, but resonance can be increased this way. All of my computer fans are decoupled from the chassis with acousti fan mounts (soft rubber), but not sure how you could do this with 15mm ply. Perhaps the silicone gasket kits? If it is the ply that is resonating, then perhaps the back ply of the cabinets needs reinforcement struts to reduce resonance. (the equivalent example in computing would be the thick steel cases which resonate less that aluminium). Check out the fan section at Silent PC Review for other ideas. Also, dB ratings on packing are worthless, but as you have stated, the fans are acceptable to you before going near the cabinet. Another good undervoltable (to 7v) fan is the Nexus 120mm.
Austen Posted March 24, 2007 Posted March 24, 2007 Another consideration is to undervolt the fans to 7v or 5v........Be aware that some fans won't start at 5v. If it works for you, don't forget a convienent source of 5v is your old Nokia 'fone charger, I am running my J35 HDD cooling fans on one........... As always, YMMV....... Austen.
Spearmint Posted March 24, 2007 Posted March 24, 2007 I’ve used 3M double sided tape in the past to mount fans. Just a word of caution make sure you get them lined up right the first time this stuff sticks like sh!t to a blanket. I currently use the plastic cable tie mounts with double sided tape on the back. His allows me to change fans more easily since it’s just a matter of replacing the cable ties.
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