Silent cooling needed for switch

[complicated]

I want to cool a 24-port switch silently or as near silently as I can. It's got two 40mm fans which whines like crazy. One blows air out of the case, while the other is the fan for the heatsink of the switch fabric. The HS is a northbridge-type and is 15mm high. The fan above it is a 40 x 40 x 10mm. There's no clearance for anything higher in the case. The case fan (mounted vertically, once again with limited extra clearance) is also 40 x 40 x 10. Both fans are actually exactly the same type (Sunon KD0504PFB2-8). Doing without some form of forced cooling seems to be out of the question... running the switch fanless for just 10 minutes or so with no load resulted in a very warm HS. What could I do? At the worst case I'm going with as many fanless hubs like the Netgear FS1xx as I need but I'd like to use this single switch if possible.

I've looked up specs on the Sunon fan and it lists it as 23dBa. I don't understand this - the fans are really whiny and loud with it. I thought they might be being overdriven but the multimeter says the driving voltage is 4.9V (fan is rated for 5V). The fan connectors are a two-pin type, and while a three-pin socket fits it looks like the fan polarity's reversed.

 

[wisdomtooth]

How about slowing down the fans? Perhaps something like the Zalman Fanmate can be adapted to work with those fans?

 

[complicated]

I've just added the bit about the fans being two-pin and reverse polarity. I've also realised that about a quarter of the whine that comes from the HSF is actaully caused by the effects of air and vibration between the HS and the F.

 

[Tiamat]

try taking a dust can to it. Maybe there is dust trapped in the bearings.

Other than that, if you dont mind modding, you could cut a hole into the top of your switch, and fit a zalman NB47J onto the chip and maybe run the thing without any fan? You would use some sort of thermal epoxy.

 

[complicated]

I already have an NB47J I'm not using so I was considering either that or cut a larger hole and stick a rewired 80mm~120mm fan on top. At 5V, even an 80mm fan should be practically silent. If there are no more elegant answers to this problem, then it looks like I'll be getting the rotary saw out. Anyone else?

 

[Tiamat]

Originally posted by: complicated
I already have an NB47J I'm not using so I was considering either that or cut a larger hole and stick a rewired 80mm~120mm fan on top. At 5V, even an 80mm fan should be practically silent. If there are no more elegant answers to this problem, then it looks like I'll be getting the rotary saw out. Anyone else?

I like your style!
Good luck!

 

[IceWindius]

Nope, hack that sucker with a jigsaw and put a quiet 80mm on that thing. I really hate our Cisco and HP switches at work, their little fans whining is farking annoying.

 

[superkdogg]

Quiet 80 is way better for cooling than quiet 40, but if you didn't want to cut it open you could always wire a rheostat in the + line to the fan and you'd have variable volatage control. Otherwise, would an old CPU HS fit and passive cool the switch? I'm asking because I don't know how hot they get.