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Old August 18, 2010, 12:16 PM
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yes, i have a small box full of em when i dont feel like taking 5.25" space :)
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Old August 18, 2010, 01:30 PM
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Find the resistance of the fan and add a resistor to it that halves the power or something.
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Old August 18, 2010, 02:08 PM
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Yes, a voltage divider takes that out of the equation as it feeds it a specific voltage you want. 12V in with a voltage divider can force it to spew out 5V, 7V, whatever i want while the 12V rail only sees its feeding a device 12V.
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Old August 18, 2010, 02:59 PM
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I haven't actually had any luck with potentiometers as fan controllers, resistors and the 5v/7v/molex trick have been working much better for me. (no buzz)
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Old August 18, 2010, 04:11 PM
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What resistor value did you use?
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Old August 18, 2010, 04:50 PM
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I just copied one of the Zalman/Noctua ones, I have a ton of resistors and random parts laying around.

Green, blue, black, gold. (I just know it ends with gold which means +/-5%)

My electronics teacher would kill me if he saw this post.

EDIT: but just in case he does see this I'll try and redeem myself by giving you this formula: current=voltage divided by resistance.

The fan will have the current on the back sticker, voltage is 12V, just change it to a value between 5-11V and do the math.
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Old August 18, 2010, 07:04 PM
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Are you sure about that, thats only a 56 Ohm resistor and that sound very very low to me
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Old August 18, 2010, 07:24 PM
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Well the math seems to work out, and a quick Google shows a pic of the Zalman adapter.

These resistors are supposed to reduce to 5-7V, depending on the fan. 7V/56Ohms=0.125A which seems about right for a typical 120mm fan. 5V/56Ohms~=0.9A which seems right for a low speed 120mm fan.
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Old August 18, 2010, 07:27 PM
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Maybe i'll use a 1k pot to find the sweet spot on a bread board before i shove in a resistor into the mix.
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Old August 19, 2010, 05:53 AM
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Remember that you have to consider the power rating of the resistor too, so be careful which ones you choose. You don't want it to overheat and blow up or degrade. I just recently grabbed a 100 ohm 100 W resistor after sending maximum power to it, and you could guess what happened after...
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