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Should i set my fans to PWM or DC


Newbuilder1

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Hi Everyone,

 

I purchased a 280x NonRGB case. It came with two 120mm fans.

I recently have been having problems with my MOBO. The fans can behave erratically by spiking to the high rpms and then dropping to 0 and then back to idle..

 

I was told these fans are PWM however they are not LED and they have 3 pins.. Doesn't this mean it should be to DC for these fans? Everything I read says a 3 pin connector should be set to DC.

 

Thank You!

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3 pin connector is DC, yes.

 

Thank you for your quick response I appreciate it!

 

I have one problem.. I have set both sys 2 and 3 fans to the same curve however sys 3 fan is always at a much lower rpm then sys fan 2 even though they are set to the same curve.. also when I max out the volts the fans do not go nearly as high in rpm when they are set to PWM, but then they bounce all over. This is seen within he bios in the fan control.

 

In icue I’m seeing sys fan 2 hit around 1900rpms with system fan 3 at 900rpm..

icue also is showing a 4th fan with Rpms however my mobo doesn’t have 4 system fans..

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If you had some 3 pin DC fans set to PWM, they should have stayed at the maximum speed all the time. PWM is a constant 12v. The erratic behavior is not consistent with this. Your control curve and variable are set in the BIOS and this often defaults to cpu temp. That may very well cause erratic behavior. You need to go in there and verify things are set equally and perhaps find a steadier solution. Also, iCUE may not be the best source of verified fan data and duplicate motherboard data is common. Make the fans are actually changing. Make sure you are not running additional monitoring software.
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If you had some 3 pin DC fans set to PWM, they should have stayed at the maximum speed all the time. PWM is a constant 12v. The erratic behavior is not consistent with this. Your control curve and variable are set in the BIOS and this often defaults to cpu temp. That may very well cause erratic behavior. You need to go in there and verify things are set equally and perhaps find a steadier solution. Also, iCUE may not be the best source of verified fan data and duplicate motherboard data is common. Make the fans are actually changing. Make sure you are not running additional monitoring software.

 

Thank you again for your quick response. I took some pictures to help explain.

 

https://ibb.co/ZGqkm7G

https://ibb.co/jGmjyCY

https://ibb.co/JnVVykK

https://ibb.co/D5vtzzq

https://ibb.co/whHFBFb

https://ibb.co/PQ3XfB8

https://ibb.co/k6fY4Ln

 

In the board explorer of my MSI BIOS. It shows sys fan 2 flashing on and off every couple of seconds or so.. This used to happen to sys fan 3 and sometimse both but in this circumstance it is only sys fan 2.. That is the first weird thing

 

Second weird thing in the graphs.. As you can see sys fan 3 should be at a higher voltage but it is very low.. sys fan 2 is bouncing all over the place when my system is idling in bios at 36 degrees.. what the heck is causing this..

 

I had my fans set to PWM for awhile, Could that have messed them up?

 

Is there a driver I should reinstall?

 

I have reset the cmos once and flashed the bios acouple times already.

 

Is my power supply failing!?

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I am not sure why the fans are dropping in and out, but one thing is for sure: Get off the the 0.1 step up/down time. You don't need case fans to react in 1/10th of a second intervals. That alone might cause it to freak out. I am surprised it even allows you to do that. You case fans affect the internal/external air exchange rate and that is a factor of internal ambient temperature. That never changes in rapid fashion. Try something like a 10 second step-up down time.

 

One of those curves uses "system" as the control variable. I have no idea what that is, but it is likely motherboard or MSI specific.

 

You don't need to keep flashing the CMOS. No, setting the fans to PWM does not mess t hem up. It just supplies a 100% control voltage until you stop. I do find it odd they were jumping around when in PWM mode. That should not have happened no matter the control settings. They should have been locked at maximum.

 

Make sure you are not running a MSI desktop version (Command Center?) that is overriding the BIOS controls.

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I am not sure why the fans are dropping in and out, but one thing is for sure: Get off the the 0.1 step up/down time. You don't need case fans to react in 1/10th of a second intervals. That alone might cause it to freak out. I am surprised it even allows you to do that. You case fans affect the internal/external air exchange rate and that is a factor of internal ambient temperature. That never changes in rapid fashion. Try something like a 10 second step-up down time.

 

One of those curves uses "system" as the control variable. I have no idea what that is, but it is likely motherboard or MSI specific.

 

You don't need to keep flashing the CMOS. No, setting the fans to PWM does not mess t hem up. It just supplies a 100% control voltage until you stop. I do find it odd they were jumping around when in PWM mode. That should not have happened no matter the control settings. They should have been locked at maximum.

 

Make sure you are not running a MSI desktop version (Command Center?) that is overriding the BIOS controls.

 

Thank you for helping me figure out this issue.. So i double checked and I have no other command center or anything running.. I also put it to system and there is no change.. What is really weird is I cannot make the fans go max RPMs either When i try this they just spike up and go back to idle speeds very quickly.. I just changed windows 10 boot from CSM to UEFI but that didnt seem to do anything either.. is it possible that my PSU is not enough?

 

What is even more weird is that this was not happening when I first bought my components. This became a thing.. Is it possible my motherboard got shorted out?

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I have more information that might help out. I downloaded dragon center and manually adjusted the two system fans..

 

I also want to mention that system fan 1 is being used by a 4 pin connector that splits to 2 tiny 60mm fans that can pull 3000 rpm and has absolutely no reading problems or weird fluctuations.

 

Now when i adjusted system 2 and 3 and put them on max the most they could go was around 1200 but online it says there max rpm is 2000 rpm.. I also get the right numbers reported but then it jumps to an extremely high number for a second. What is really really weird when I put sys fan 2 and 3 on PWM mode then i can hear them actually kicking up but on DC i cannot bring the voltage up a certain amount i guess.

 

https://ibb.co/Scqs82T

https://ibb.co/dgWvyx4

https://ibb.co/XtrmCf8

https://ibb.co/DkF2w31

Edited by Newbuilder1
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Exactly which fans do you have?

And keep in mind that there is a limited amount of assistance that we can provide with MSI's tools - they just aren't something that many of us are familiar with here. For MSI/Dragon Center issues, the MSI forum is likely a better place. Not saying this to tell you off or anything - we'll do what we can - just understand that there are limits to our knowledge of the software that you are using.

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I have the fans that came with the Corsair 280x nonrgb case. They are 120mm's

 

on the interor side of the fans there is this number 31-004801

followed by

 

31-004801

 

These are not RGB fans

 

The max speed is 2000rpm right or am i wrong?

Edited by Newbuilder1
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Exactly which fans do you have?

And keep in mind that there is a limited amount of assistance that we can provide with MSI's tools - they just aren't something that many of us are familiar with here. For MSI/Dragon Center issues, the MSI forum is likely a better place. Not saying this to tell you off or anything - we'll do what we can - just understand that there are limits to our knowledge of the software that you are using.

 

 

yeah i totally get in no worries.

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