How can I slow down 120mm fans with molex connectors ??

Jason404 · Post by **Jason404** » Mon Aug 14, 2006 7:52 pm

I have just bought a Thermaltake Armor full tower case that comes with a couple of 120mm blue LED fans. They look pretty cool, but they are too noisy. They spin at around 1450-1490 rpm according to the Asus motherboard software that I am using. I have other components that I want to quieten down, but these fans are the noisiest bits, by far.

The problem is that they have 4-pin molex connectors as well as a single yellow wire to go the the three pin connectors on the motherboard for speed measurement. What is the point of that?? I can't use the Qfan2 feature that my Asus motherboard has to slow down case fans when they don't need to blow so hard, and I can't connect them to a fan controller. What can I do? Is there a way to hack them and rewire them somehow? Replacement 120mm fans don't seem that cheap.

Howard · Post by **Howard** » Mon Aug 14, 2006 8:06 pm

Couldn't you just plug the 4-pin connectors into a fan controller?

Yate Loon D12SL-12 fans are $4 at Jab-tech, btw.

JohnnyWakko · Post by **JohnnyWakko** » Mon Aug 14, 2006 8:21 pm

Howard

I think he is referring to the other 4pin connectors, the molex:

MOLEX

I too have these in my Antec180b and would be interested to know how to plug them into a Fan Controller that doesn;t have the molex connectors.

Is this what your asking Schnapps Syndrome?

Howard · Post by **Howard** » Mon Aug 14, 2006 8:25 pm

Well then, get a fan controller that decreases voltage (through resistance), not one that uses PWM to decrease speed.

JohnnyWakko · Post by **JohnnyWakko** » Mon Aug 14, 2006 8:38 pm

Howard wrote:Well then, get a fan controller that decreases voltage (through resistance), not one that uses PWM to decrease speed.

"Alrighty then folks. We are now into the bonus round. Are our contestants ready for the next question? Ok! Here it is folks! The next question for our Very Important Perons is....

(DRUM ROLL)

"What's PMW?"

(INSERT GAME SHOW ORGAN SOUND, and CANNED APPLAUSE.)

Lawrence Lee · Post by **Lawrence Lee** » Mon Aug 14, 2006 10:50 pm

There's a simple way to do a 7V or 5V mod on a 4-pin connector. Google "7v mod."

Bluefront · Post by **Bluefront** » Tue Aug 15, 2006 1:33 am

Wakko....it would be easier to replace the noisy fans with better units. About $12 will get you two Yate Loons at JabTech.

PWM....pulse width modulation. Sounds more difficult than it is. It is a method to regulate fan voltage, without using heat-producing resistors. Basically the 12v going to a fan is pulsed on/off, the longer the 12v is on, the higher the voltage the fan recieves. If the on/off cycles are of equal time (for example) the fan is running at 6V.

Pros....fans can start at really low voltage, no extra heat, no heatsinks.

Cons....some fans will make extra noise running on PWM voltage.

Check out this PWM fan controller......cheap enough?

zenboy · Post by **zenboy** » Tue Aug 15, 2006 12:31 pm

Second the 7V mod, it's got the best price/performance ratio of any of these. If it's like an Antec Tri-cool, you can just fidget the black wire (ground) out and move it over to the far end (where the red wire comes in). Bingo, fans @ 7V.

Howard · Post by **Howard** » Wed Aug 16, 2006 10:41 am

Bluefront wrote:Wakko....it would be easier to replace the noisy fans with better units. About $12 will get you two Yate Loons at JabTech.

PWM....pulse width modulation. Sounds more difficult than it is. It is a method to regulate fan voltage, without using heat-producing resistors. Basically the 12v going to a fan is pulsed on/off, the longer the 12v is on, the higher the voltage the fan recieves. If the on/off cycles are of equal time (for example) the fan is running at 6V.

Actually, (AFAIK) the voltage is always 12V, but it's pulsed. A higher duty cycle = higher speed, kinda like a microwave oven (also uses PWM for non-max heating)

Bluefront · Post by **Bluefront** » Wed Aug 16, 2006 2:50 pm

Well yeah...it's always 12V, just pulsed. Seems to me though, if you check the voltage with a VOM, it will measure the perceived voltage.....like 6V if the on/off cycles are equal.

zenboy · Post by **zenboy** » Wed Aug 16, 2006 2:56 pm

My digital multimeter almost always reports my Vantec PWM's output as something like "11.35V", but an analog meter actually seems to fluctuate the "effective voltage".

disphenoidal · Post by **disphenoidal** » Fri Aug 18, 2006 12:27 pm

Cpemma has schematics for a stylish DIY PWM fan controller. He's got lots of neat designs.

I just use an adapter on my molex fans so I can plug them into a fanmate, cost something like $2.