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Thread: Controlling regular fans from MOBO outputs




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    Question Controlling regular fans from MOBO outputs

    Hi all, newbbie here. I've just bought a GA-P55-UD3P mobo, which has the capability to measure/(control?) to system fans. The problem is that after a fast research (CFM/dBA...) I purchased today two Thermaltake Thunderblade A1926 (main cabinet 120mm), which, according to the specs, are quipied witha 4 Pin connector, which I assumed (wrongly) that was the four pins to the MoBo's SysFan's 1. My surprise was big when I saw that it is actually a PS molex connector!! and the "inteligent wiring" is just a 3 pin with only 1 wired to measure the RPM. I'm not sure (and MOBO manual is quite poor on this aspect) about the two power pins on the MOBOs output (fourth one is actually "reserved"). I assumed that only the CPU one is controlled via PWM, and for sysfans the speed control (if any...) is only done varying voltage. In any case, might I wire (using proper connectors, of course) the two other pins from MOBO to thefeeding one on the fan? Will the mobo decrease the speed decreasing the voltage: I assume that the "starter voltage" on specs means that needs at least 6V to operate, hence I guess that with any valkue between 6 and 12 the spped will vary. And if it is PWM, why a special fan is needed, if actually changing the pulse width I can actually decrease the average (that's not the word but I don't remember it :( ) value?


    If anyone can help, I would appreciatte it.

    Thanks in Advance

  2. #2
    Lsdmeasap's Avatar
    Lsdmeasap is offline GIGABYTE Guru
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    Default Re: Controlling regular fans from MOBO outputs

    I have used those fans, and understand what you are asking. What will happen if you add the 3rd RPM wire into a 3pin connector for example will be just that, it will run as a normal 3 pin fan. Which of course you can use on a 4 pin header, but in order to control that fan you would need to set the BIOS fan control to Voltage instead of PWM as it would not be a PWM Controlled fan.

    Yes they will vary with voltages applied and if you do not use them on a fan controller, which I suggest, then they will run at full speed (Or less if you connect two to one connection). They are loud

    If I have not fully answered your question, please do let me know what else you would like to know.

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    Default Re: Controlling regular fans from MOBO outputs

    Thanks Lsdmeasap for the reply. The fact is that my MOBO's documentation is quite confuse/limited on that matter. It is clear to me the issue with the RPM sensor and the 3 and 4 pins, but the only PWM/voltage setting availabe is for CPU Fan, not for System ones. But on MOBO's pinout for SYSFAN2, it states "+12V / Speed Control", hence, It is only voltage control and that's why there are no seeting on BIOS? But why it is not even mentioned on SMART Fan feature? What about SYS FAN1, the +12 is only power (relevant if at least SYS FAN2 is contraolable)?
    I'm not finding on BIOS nor Gigabyte's applications any way to manually control/enable/set speed for those FANs

    Thanks

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    Default Re: Controlling regular fans from MOBO outputs

    Yes, only the CPU fan would you be able to change the method in the BIOS, however the other 4pin case fan adapters will run as voltage/3 pin if that is all that is connected to them.

    Sys_fan 2 always seems to have issues, so if this is the connector you are trying to use you may just need to use a different one if yours seems to be slow.

    The other fan headers such as Sys_fan 1, PSU Fan, NB Fan, ect all will be voltage only I believe unless P55 maybe has an additional 4 Pin header. Easytune is labeled that way because some of the models do have more voltage controls over these fans such as the UD4P, UD5, UD6. They allow Smart Case and CPU fan control, the boards whose BIOS do not offer this for case fans will be set always to PWM, that way if PWM is connected it will function properly and if 3 pin is connected it will function as voltage

    Easytune 6, will allow you to manage your CPU fan only. Do you need help with that, or was you specifically looking for Sys_Fan 2 help?

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    Default Re: Controlling regular fans from MOBO outputs

    Thanks again Lsdmeasap for the reply. I just finished seeing my case. I connected in paralell both fans to SysFan 2 power (i've read here an interesing post realted to that), but with the RPM sensors to its own connector. Hence, the MOBO will have control over both FANs (not indeoendently, but both anyway ) while I'll be able to monitor failures over any of them. I also did set my case's temperature activated fans to two 80 mm ones on the side panel, and the manual fan speed control of the case controlling the HD coolers.

    Thanks again

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    Default Re: Controlling regular fans from MOBO outputs

    Well so you know, RPM Sensor is just that, and only outputs RPM and then only relays back voltage control to that plug. So using a different RPM Plug that the fans are not connected to wont help things much.

    Did you test SYS-FAN 2 with a single fan, you should, it may be ok. Then if so you can just hook it all up to that

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