Wow, my first instructable so please be gentle.

My home network contains, among other things, a NAS device.
This is a device that you would run 24x7 for general availability right ?
However I prefer to keep this device in the living room, because that's where the 1Gb ethernet switch is located.
After a couple of months the noises that the device produces became too loud and annoying, so time to call in the help of Tinkerboy.

Step 1: Find the Noisy Component.

Well the high pitch whine told me it was either the disk or the fan.
Upon opening the case (oops there goes the warranty) I did a swift aural inspection with the NAS running.
In fact the noises had two sources:
-the vibration from the hard drive
-a cheap small fan running at full speed.

Step 2: What to Do About the Fan?

The disk vibration was actually caused by loose screws, so that was easily fixed.

Next the fan: how to reduce its noise?

I could think of the following options :
-replace with quieter model
-reduce fan speed.

I opted for the second, knowing that the spare small fans I had were equally noisy.

The preferred option would have been to get a smart speed control, but this would have to be completely self-supporting and a design was not readily at hand.

So eventually I opted for the simplest: reduce the fan speed by adding a resistor.
This reduces overall airflow so introduces the risk of overheating. But the NAS webpages show the temperature of the disk, so I decided I could monitor if cooling is sufficient using that information.

Step 3: Deciding on the Right Resistor.

To decide what would be the right resitor I simpy expermented.
I hookd the fan up with a 12 powersupply and added some resistors to find the best result as far as noise and reasonable fanspeed were concerned.

I found a 56 ohms resistor (green-blue-black-gold) giving sufficient speed reduction to get rid of the whining noise while maintaining a reasonable fan-speed.

I also took a small piece of white insulation to fit tightly over the resistor, so none of the bare metal can cause any problems.

Step 4: Adding the Resistor.

Adding the resistor requires only a very little bit of soldering work, so it should not be too challenging for the average instructables audience.
First break the circuit by cutting one of the wires running from the board to the fan. We're not disassembling a bomb, so red or black are both ok.
Strip both ends of a small section of isolation, and solder one end to the resistor.
Slip the tight fitting tube all the way over the resistor and solder the other end.
Then slide the tube back, covering all bare metal.
Realy posh tinkerers would use shrink tubing, naturally.
As the last image shows the result is an odd whit tube that fits snug in the corner of the case.

Step 5: Putting Everything Back Together.

Now put all the bits and pieces back where they belong.
In my case: hdd-bracket (4xscrew) hdd (4x screw) hdd: power and ata connectors
I left the case open for the first trial run. Everything works as it should , but with less whining noise!

Step 6: Finaly

Whit the case closed again I watched the disk- temperature for a while, but it sits steadily at 87F / 30C. That's what it allways has been, so success!
Good job. In my homemade FreeNAS i added a variable 5w wirewound resistor in series to optimise cooling/sound ratio. Works well.
Wouldn't it be even better for both the cooling and noise to just put in a bigger fan? I don't really know how big that one is, but you should be able to put a 140/120 mm Antec tricool in there, which are silent, and you can easily change the fan speed if it gets too hot.
Well my solution is free, and this case fan is a tiny 40x40 fan. I don't know of any such elegant solutions in that size. Modifying the case for a much larger fan would have quite an impact on the design. Your comment does remind me to add some scale reference to pictures in the future, just to show what the size of things are.
Awesome project - My initial thought is nix the fan, and nix the outer case for one with a bajillion holes in it. Enter: the drill press :D

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