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Discussion Starter · #1 ·
I'm installing my new HTPC. I'm using the Silverstone LC17, and it has 2 80mm fans, the connector is not the molex, but the 3 pin that are supposed to be connected to the motherboard.


I think the fan is to loud, so I'm thinking about modding it to 5 or 7 volts, and connect it to a standard molex.


How do I do this hack ?
 

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Which mb are you using? Controlling fan speeds by SpeedFan is the most intelligent and flexible method.
 

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I have to advise against doing the 7v mod, I've done it, several times in the past, and about 70% of time it works just fine, another 20% of the time it shorts your power supply and the system won't boot until you remove it, the last 10% of the time, it releases the magical white smoke from your power supply and you have to go get a new one. IMHO it's just not worth the risk if you don't know for sure how your power supply is laid out and whether or not it can handle it.


For 5v though, all you need is a standard 3 pin male to 4 pin molex adapter, you can either buy them set up for 5v or you can buy a standard 12v one and swap the wires over to the 5v side of the molex connector. If you want a cheap and easy solution you can pick up a Zalman ZM-MC1 for stupid cheap anymore.
 

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The third pin, as u probly already know, is the RPM readout. Assume the "system" runs on 12v, the readout pin either references the ground (most likely) or the 12v. So if u change the reference, unpredictable things will occur. The 7volt mod changes the ground reference, which should work fine if u don't use the third pin. My personal experience with 7volts is, half of the time it doesn't provide enuff ommmph to start up the motor, and certainly a 12v fan won't run on 5v at all.


You can use the other controls as other have suggested. But if u wanna keep things simple, use a 5 watt, 31-50 ohm resistor in series on the 12v rail will bring the voltage down to ~8-9 volts, and no reference is changed and keep using the third pin.
 

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I assume you mobo does not have any speed control on the system or case fan pins or any speed control software. Or do like I did on one of my old cases. Assuming a 3 pin cpu fan. Install a 3 pin Y harness on the CPU header ($2). One is leg is 3 pin and the other is 2 pin. Hook the case fan up to the 2 pin leg. Enable your mobo smart fan controller that speeds up the cpu fan in response to cpu temp. Then when your cpu fan speeds up so does your case fan. In my case they seldom get above minimum.


BB
 

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I've used these 12v to 7v adapters with my 12v panaflo fans for many years with no problems. It is pretty much idiot proof.
 

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Throw u a monkey wrench...


I spent time and effort making my box quiet... know that my next build is gonna be passive cooled... heatpipe + huge heatsinks, that's gonna be TRULY silent. Maybe chirp from the 2.5 drive but that's is.


Quiet fans alone is not the only variable... the case comes into consideration too. Thin metal that resonates. The mounting location of the components may create a swoop-swoop noise. As your quiet fans wear, they WILL then start making more noise too. Too many variables.


Quiet fans is for stop-gap, budget solution. The ultimate quiet is, passive cooled. When time and $ are no object.
 

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Discussion Starter · #11 ·
Well, it seems that speedfan dosn't work with my mobo.

Guess I'll either have to try a 5 volt hack .. .or get some sort of controller, just seems like a ***** to have 3 controllers behind the table
 

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Quote:
Originally Posted by MrBobb /forum/post/16919877


My personal experience with 7volts is, half of the time it doesn't provide enuff ommmph to start up the motor, and certainly a 12v fan won't run on 5v at all.

This depends widely on the fan itself. I don't think I have a single fan that won't start at 7v though. I do have several that won't start at 5v though. The better quality the fan the better chances you have of the motor being more sensitive to the power provided. I have several Scythe Slipstreams that will start all the way down to just below 4v. I also have some older Arctic Cooling fans that were free that won't start below about 6.3-6.5 volts, they're among the worst I own.
 

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Quote:
Originally Posted by charlesj123 /forum/post/16924463


Myself,


I don't recommend using your fans on the 5 volt circuit, I did it and had electro magnetic noise on my TV uppon HDD access. Removing the fans fixed the problem.


Charles

Hard drives are magnets, as are fans, and the motors in you optical drive, sounds like it was either an odd interference from wiring location or a coincidence.
 
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