Solved

Case Fan control not working?

Hello, I own a H81m-p33 mobo from msi, I recently bought this little 80mm fan: https://www.amazon.ca/gp/product/B003MDQAI8/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

and I could not lower its RPM for some reasons. I tried doing it in the BIOS and with SpeedFan but it still spins at 1700 RPM (100%) and it can be quite noisy.

Thanks.
12 answers Last reply Best Answer
More about case fan control working
  1. Is it possible I should have bought a fan that has 4 pins? 1 for the +V, the other for -V, another for sending data and the last to receive data?
  2. You're using the 3pin fan connector into the motherboard, correct?

    The MOLEX will supply constant voltage if you're using that, you'll need a resistor.
  3. greens said:
    You're using the 3pin fan connector into the motherboard, correct?

    The MOLEX will supply constant voltage if you're using that, you'll need a resistor.


    I am indeed using the 3pin fan connector... Should I be using a resistor for the molex while using a 3pin or when I'm only using a molex? I didn't really understand your last sentence.
  4. Naw you only want to use one or the other. If you're using a 3pin there should be no need for a resistor. A resistor is just the only way to reduce voltage supplied by MOLEX, but if you're using the 3 pin we don't need to worry about that.

    I'm guessing you turned it all the way down to 0 and it still spun at full speed?
    It is possible that even with the lowest voltage supplied it is still enough to make the fan spin full speed, but that would be kind of unusual. You can always say screw it and get a 3pin resistor and call it a day.
    https://www.amazon.com/uxcell-Noise-Reduction-Cable-Cooling/dp/B007PPHKO2
  5. greens said:
    Naw you only want to use one or the other. If you're using a 3pin there should be no need for a resistor. A resistor is just the only way to reduce voltage supplied by MOLEX, but if you're using the 3 pin we don't need to worry about that.

    I'm guessing you turned it all the way down to 0 and it still spun at full speed?
    It is possible that even with the lowest voltage supplied it is still enough to make the fan spin full speed, but that would be kind of unusual. You can always say screw it and get a 3pin resistor and call it a day.
    https://www.amazon.com/uxcell-Noise-Reduction-Cable-Cooling/dp/B007PPHKO2



    Well, in my Bios I have the option to choose at what % it stays, and I chose 50% for minimum and 60% for maximum but the fan still spins at full speed (1700 RPM). I also set the option for the fan to not care about the temperature but to just spin at defined speeds forever pretty much.
  6. Hmm, can you just decrease the %? Does it run at 1700 if you have it at say, 10% fan speed?
  7. greens said:
    Hmm, can you just decrease the %? Does it run at 1700 if you have it at say, 10% fan speed?


    Well, I can't set it lower than 50% in the BIOS and yeah, even at 50% it spins at 1700 RPM when it ( I think so, unless I really suck at math) should spin at 850 RPM.
  8. Well i think the problem is that the bios doesn't actually know the fan's speed. It only knows what a typical fan's power demands are. A 220mm fan might be running at 30% when you set it to 50% because of the larger demand of the fan.
    Your little 80mm is still running full speed at half power, which means it was probably only using half the power supplied to it in the first place.

    I think that a resistor (or two) is your best option. I bet that once you have a couple resistors on your fan control will work. It will decrease the upper limits of the power, so when you set it to 50% the fan actually gets 25% power and the speed will decrease. If you set it to 100% the fan actually gets 50% and continues to run at full speed.

    Hopefully that makes sense. I believe the 80mm fan just uses so little power that your BIOS doesn't have a setting low enough.
  9. greens said:
    Well i think the problem is that the bios doesn't actually know the fan's speed. It only knows what a typical fan's power demands are. A 220mm fan might be running at 30% when you set it to 50% because of the larger demand of the fan.
    Your little 80mm is still running full speed at half power, which means it was probably only using half the power supplied to it in the first place.

    I think that a resistor (or two) is your best option. I bet that once you have a couple resistors on your fan control will work. It will decrease the upper limits of the power, so when you set it to 50% the fan actually gets 25% power and the speed will decrease. If you set it to 100% the fan actually gets 50% and continues to run at full speed.

    Hopefully that makes sense. I believe the 80mm fan just uses so little power that your BIOS doesn't have a setting low enough.



    Weird, because when testing the CPU power it worked well.
  10. CPU probably has a 120mm fan. It could be that the bios setting just isn't sticking or something.
    CPU fans also have a PWM function (they are 4 pin) and variable fan speeds work really well with CPU fans.

    I bet if you plug the 80mm fan into the CPU fan slot it will be at 1700RPM still.
  11. Actually, I think it's because I'm using a 3 pin fan. I've made some research and saw that for the 3pin connector the yellow is for the signal (show how much RPM), the red for 12V and black is the ground. What I need is a 4 pin connector. which would be gnd = black; 12V = yellow; green = signal and blue = control.
  12. Best answer
    Kahlo kahlow said:
    Actually, I think it's because I'm using a 3 pin fan. I've made some research and saw that for the 3pin connector the yellow is for the signal (show how much RPM), the red for 12V and black is the ground. What I need is a 4 pin connector. which would be gnd = black; 12V = yellow; green = signal and blue = control.


    If the motherboard has a 4 pin in that location it could totally be why! PWM control is different. It sends a signal telling the fan how fast to run.

    That said, most motherboards are still able to alter 3 pin fan speed from the bios by simply lowering voltage. That doesn't mean yours can though and a 4 pin might totally fix it!
Ask a new question

Read More

Cases MSI-Microstar Fan Controller