Guide to the 7v Fan Mod

[cetoole]

I want to ask a question:

Example:
YS Tech 120mm fan with a specs for 12V as:
4200 RPM , 131 CFM , 45db

When you volt mod it, everything should be lower by 7/12 ?? ( 76CFM, 27db, 2450 RPM )???
Is it how it work ?

If the fan has 3 pin , how could I change to 7V and where do I plug into ? Do I plug into the regular 12V power molex from the power supply ?

Many thanks

I am not positive, but I believe that the airflow and rpm comes close to that reduction, but dba is on a log scale, so is different. To use a 3 pin fan, you have to get an adapter to power the fan from a standard 4 pin molex, and do the mod on the adapter.

 

[texp4]

I just modded my YS Tech 120mm to 7V
Voila, very quiet, push air pretty good
I wish that if it could pust out 7/12 of its total CFM, it would be like 76. It is so quiet now.

 

[pswart]

I have 3 x 50mm fans in my case. Will I need a seperate power supply for each or can I use one conector (7v mod) split into tree sets of wires powering each.

 

[Amarkarian]

goood guide

 

[SIX ZERO X 3]

sweet guide did this on my desktop....i dont think u can do it but can this be done with laptop fans...like running them at 7v

 

[cetoole]

I dont see a reason it wouldnt work with laptops, expect that possibly there isnt an easily accessable +5v rail to use. I would not suggest doing it either, most laptops dont have much in the way of spare cooling available, reduce the already limited fans, and something might burn. They also dont tend to have as much drawing current as a desktop to be able to handle the mod safely, so if you must slow down you laptop fans, I would do it via resistors or voltage regulation, an easy method would be something like a 78xx fixed voltage regulator, where the "xx" is the voltage (eg. 7805=+5v regulated output).

 

[mich43L]

expect that possibly there isnt an easily accessable +5v rail to use.

Usb port.

On some laptops (dells especially) you can control the fan speeds through software.

3 pin fan connectors are only the 12v, ground, and tach signal, so you can't directly mod them. You can however use a 4 pin molex adapter to do the mod, just switch the correct wires on that and plug the fan in.

You can avoid buying an 3pin to 4 pin adapter to do the mod by taking out the pins from the 3-pin connector (push on them from the back) and inserting them directly into the female psu connector as shown here:
http://www.streamload.com/nissmo300/site/volts.htm

They're easy to insert and stay on pretty tight but are a little harder to take out.

The advantage of doing this over using a 4 pin adapter is that you can still use the rpm monitor pin in the 3 pin connector by inserting it to the motherboard.

 

[amer1337]

tried the 7v mod with an old fan and an at power supply and it didnt work why not . it worked with 12v and with 5v i tried it both ways

 

[Espion]

When I use this mod with my tornado, it won't read the RPM when it's at 7v. 12v and 5v work fine, but for some reason it's only at 7v that it won't read the RPM.

5v gives me around the same performance as the fan I was already using, and 12v gives me much better cooling(only it's too loud). So I'm interested in seeing the results for 7v only it won't work. Any ideas?

 

[four4875]

the fan's RPM sensor wire works by pulsing ground twice every revolution, so the sensor on th motherboard is looking for a logic low (0V, ground) but instead of pulling low, the fan is pulsing that line with +5V, which is definately logic high, which is what the sensor is already at, so it wont read RPMs. it could actually cause damage to the boards sensor, i would leave it unhooked.

im sure it wouldnt be too terribly difficuly to build a simple circuit to give the mobo the ground it's looking for, basically just a transistor to connect the ground to the rpm header when the fan pulses it's 5 V (or 3.3 if using that rail)

hope this helps some. only way to find out what rpms it runs at with a given voltage is to use a rheostat or other fan controlling device that actually reduces the voltage and use a multimeter to get it set to the appropriate voltage and then check with the mobo tool.

 

[Espion]

Would the mobo not knowing the RPM effect the temperature sensors as well? I get about the same results with either, even though it seems to spin a lot faster at 7v. It moves at ~2350RPM with 5v.

 

[four4875]

i dont think it would effct the temp sensors, although there might not be much of a diffi n temps with it at 5 or 7 volts.

 

[ChonChon]

i dont know how to actually get the wires out and change them. i cant seem to take out the pins...

 

[ChonChon]

well i got them out...but i pulled them from the bottom...is this wrong? if so...what do i do?

 

[ChonChon]

i dont know which connector is from where.

do i need to mod any power cables that come FROM the PSU at ALL? or are all the changed done to the 2 little ones (one in and one out) from the FAN itself?

 

[ChonChon]

i FINALLY got it with THIS GUIDE:

http://www.virtual-hideout.net/guides/7v_12v_baybus/print.htm

so easy!

 

[papercutout]

yeah, the easiest way i've found of removing the pins is using a small biro without the pen inside, and slotting it over, wiggling it around, and hoping all the thingy's have popped in, and pulling it out...

 

[four4875]

biro? is that the equivelant of say a bic pen? ive used the ink tube thinger as solidxsnake demonstrated somewhere around here, and had luck with it.

 

[Cjwinnit]

There is a better way of modding pass-through connectors. Pics soon hopefully...

 

[Skeith]

this is an easy way to do it yes, but if somone has a bit of knowledge in electronics you can easily set up a NE555 timer as a PWM modulator with a transistor and controll your fan speeds very acurately. If anyone is interested let me know and ill post the information. PWM (pulse width modulation) is very acurate and can run a fans speed slower than a voltage modification, because the PWM controller runs the fan at its desired voltage the fan will start at very low speeds.