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Old 12-31-2008, 04:43 PM   #1 (permalink)
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Default Case Fan Speed Control and Monitoring

So I just recently bought a fan for my case. It was really loud. So I have been doing research to reduce the speed of the fan so it's not so loud.

1.
If the fan is connected to the motherboard is there a way to control the RPM of the fan by use of software? I am talking about the standard 3-wire fan connector (red, black, yellow). It seems like the motherboard might have the ability to control the voltage supplied. Or it could apply a duty cycle. I know this is somewhat possible because the cpu fan (4pin) is temperature controlled.

2.
I did find a way to adjust the speed by rewiring the fan, from this website: http://www.hardwaresecrets.com/article/496/. Using 5v, 7v, and 12v. I can get RPM readings for the 5v and 12v settings, but for the 7v I don't get a reading. The only thing that I can think of is that the negative terminal is not connected to ground.

Am I correct in assuming that that is the reason?

3.
I am aware of hardware addons to be able to vary fan speeds. I am just cheap and am not going to buy them. But I was curious, some of the items I saw for sale had dials. So I was wondering how they worked. Is it just a potentiometer? Not a big deal, just something I thought of while typing. Kinda curious.


So my 2 questions are:
Can I control the speed of my fan by use of software?
Why can I not read the RPM of the fan at 7v? (not grounded?)


Thanks!
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Old 12-31-2008, 05:20 PM   #2 (permalink)
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Default Re: Case Fan Speed Control and Monitoring

The one program used often for controlling fans is called SpeedFan found at Download SpeedFan - Access temperature sensor in your computer

How is the 7v fan being powered? off the board or directly from the supply? If the fan is powere directly from the supply the board can't monitor the fan speed. Cases and cpu fans plugged into the board directly are monitored in the bios.
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Old 12-31-2008, 07:09 PM   #3 (permalink)
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Default Re: Case Fan Speed Control and Monitoring

to solve this the easy way...buy a quiet fan...
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Old 12-31-2008, 07:23 PM   #4 (permalink)
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Default Re: Case Fan Speed Control and Monitoring

"noisey fan you're through! get lost!" Grrr... "I found a new replacement fan that starts monday!"
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Old 12-31-2008, 07:25 PM   #5 (permalink)
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Default Re: Case Fan Speed Control and Monitoring

thats what im sayin man...
you ever date a girl and you were like "she would be perfect if only _____ "?
and so you tried to make her stop (or start) doing ____
and eventually you gave up and then you met someone who just did ___
and it was like "i knew there were women that were like this..."
fans are the same way heh heh heh.
welcome to nagasama's new year's posting party.
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Old 12-31-2008, 10:10 PM   #6 (permalink)
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Default Re: Case Fan Speed Control and Monitoring

Quote:
Originally Posted by eyeCpc View Post

How is the 7v fan being powered? off the board or directly from the supply? If the fan is powere directly from the supply the board can't monitor the fan speed. Cases and cpu fans plugged into the board directly are monitored in the bios.
Not completely correct.

3pin fan connector pins: red is positive terminal, black is negative terminal, and yellow is the sensor.

4pin Molex connector (from the PSU): red is 12v, yellow is 5v, and black is ground (or 0v).

So for a 12v fan I have the red fan wire in the yellow hole and black in the black. 5v fan I have the red in red and black in black. for the 7v connector i have the red fan wire in the yellow hole, and the black wire in the 5v connector. 12-5=7.

If I want to monitor the speeds at the different voltages I put the yellow wire into the motherboard. This method works for 12 and 5 volts, but for the 7 volts I just get a reading of 0RPM (but i can obviously tell that it is not 0 RPMs because the fan is moving). So i am guessing since the 7 volts is not grounded that is somehow interfering with the speed sensor.


Quote:
Originally Posted by Nagasama View Post
to solve this the easy way...buy a quiet fan...
I could do this, but that would mean spending money. Or going out and returning this fan, and then ordering a new one online. Neither of which I want to do. Besides the easiest way of doing something isn't always the best. The main reason why I am asking is just out of curiosity.



I can only figure out how to control the speed of my cpu fan, nothing else. IDK, maybe I have to fiddle around with it a little more.
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Old 01-01-2009, 01:02 PM   #7 (permalink)
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Default Re: Case Fan Speed Control and Monitoring

then i would have to agree with your assesment that if the 7V is not grounded, and the others are...and you get an RPM reading from the voltages that ARE grounded but not from the voltage that ISNT grounded...that the lack of a ground would be the culprit.
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