[SOLVED] Why is one of my fans turning off and immediately back on very often?

divinewarax

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Jul 21, 2018
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Whether I'm on my desktop or playing a game one of my RGB Cooler Master chassis fans will go blank (rgb turns off) and the fan drops to 0 rpm. Before it even has time to come to a stop it will power back on and the color comes back. This all happens withing about a second total. The frequency it happens is usually every few minutes but less often when I'm just idling at desktop. Very annoying and starting to worry me.

This is a new issue. I've had the fans just over a year now, along with the PC itself. It was all built together. I did take apart some things to install an SSD recently but it all works fine except for this and the fan started doing this a couple weeks afterwards so I figure it can't be something I did while reassembling it. I've tried going through the BIOS and running the fan test twice but that didn't help.

My theory is that for some reason the voltage to that particular fan drops below what it can handle and it momentarily shuts off. But then why would it be happening while gaming when the fans are running at higher RPMs?

Any help would be much appreciated as I can't figure it out and I don't want it to go unsolved or have a bigger underlying issue.
 
Solution
My first thought, also, was that the fan is receiving a minimum speed signal so low that it stalls, and then the fan header detects fan stalling and gives it a quick high-speed signal to re-start it. BUT my suspicions are aroused by your statement that, "chassis fans will go blank (rgb turns off) and the fan drops to 0 rpm. Before it even has time to come to a stop it will power back on and the color comes back." A too-slow speed signal would have NO impact on the RGB lights! So I'm thinking more about a poor intermittent Ground connection that might impact both fan motor and RGB lights. But then I'm thinking, the RGB lights normally have their own separate Ground line, so that also should not happen.

That leads me to ask: please tell...
make sure the cable is still firmly attached to the fan port.

is this a DC or PWM fan?
for PWM fan curves the lowest setting can be too low for the fan to power up. somehow the curve profile could have been altered; by BIOS update, etc. and it may be referencing a temperature other than the CPU, so it may not be running at the desired times/speeds.
maybe try a different fan port. or create a new more efficient fan curve profile either in the BIOS or within any motherboard control software.
 
Last edited:

Paperdoc

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My first thought, also, was that the fan is receiving a minimum speed signal so low that it stalls, and then the fan header detects fan stalling and gives it a quick high-speed signal to re-start it. BUT my suspicions are aroused by your statement that, "chassis fans will go blank (rgb turns off) and the fan drops to 0 rpm. Before it even has time to come to a stop it will power back on and the color comes back." A too-slow speed signal would have NO impact on the RGB lights! So I'm thinking more about a poor intermittent Ground connection that might impact both fan motor and RGB lights. But then I'm thinking, the RGB lights normally have their own separate Ground line, so that also should not happen.

That leads me to ask: please tell us exactly what fan you have - model number if possible. My reason for asking is that MAYBE you do not have RGB fans at all. Other fan designs might show these symptoms.

The first fan design that included lights in the fan frame were termed "LED Fans". In those, the LED lights normally were of one colour only in a fan and they never changed colour or blinked or any fancy display. The fan had only ONE cable to plug into the mobo. The LED's In those are wired in parallel with the fan motor and simply light whenever the fan has power. Many of them were dimmer when the fan was sent a lower voltage to run more slowly. That type of fan certainly can have both motor and lights fail and re-start at the same time.

What we now call plain RGB fans are ones that have three LED colours in the frame and TWO cables - one for the motor only that plugs into a mobo fan header, plus a cable for the lights that ends in a wider 4-pin (12 VDC system) female connector that plugs into a different 4-pin plain RGB header on the mobo. In this system only one light colour can be displayed at any one moment all around the fan, but that can be changed over time.

The fancier new type are called Addressable RGB or ADDR RGB or ARGB, and they also have two cables. BUT the RGB cable with the wider connector has only THREE holes and goes to an ADDR RGB mobo header with only three pins that provides 5 VDC power plus display control. It can do much more complex lighting effects like several colours simultaneously in the fan, and colour patterns chasing around.

So, exactly what type of "RGB Fan" do you have? If you cannot tell us model number, tell us about the cables and the count of holes in the wider RGB connector (IF there is a separate RGB cable).
 
Solution

divinewarax

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Jul 21, 2018
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Alright, apologies for the late info.

I have the Cooler MasterFan Pro 120 Air Balance RGB. there are three of them. Top, back, and one of the intake fans on the front. The other front intake fan is controlled by a CoolTouch-E display I have on top of the PC case but that (at least I assume) isn't related. I have the fans plugged in to, I'm pretty sure, the same place I had them before I installed the SSD and did some cable management. As you guys suggested, I have gone through more than 8 times, some before I posted the thread and some after, modifying the fan curves for all three CoolerMasters through the Asus BIOS Q-Fan control. They all have minimum speed based on Temp of around 40%. So it must not be that I have it set lower than the fans will allow, at least I think? And yes, there is a seperate cable for RGB that goes to the RGB connector.

I'm not exactly sure how to tell what it's adjusting speed based on , but I see the speed fluctuate with the CPU temp so I assume it's that. I do know for sure that they are in PWM mode as that is what allows me to adjust fan curves in the BIOS. Things are basically set up the same as I had it before taking some things apart and doing the cable management. Which is why it's one of the more difficult issues for me to solve myself. I simply have no idea what could be causing this.

One final note, I really started paying attention to the RGB brightness and it's correlation to the speed of the fan and it DEFINITELY gets dimmer and brighter based on the fan running slower or faster respectively.
 

Paperdoc

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On the Cooler Master website, the only MasterFan Pro Air Balance fans I can find have NO lighting in them at all. If I look instead for their RGB fans, there are MF and SF series, but none under the Pro name.

I am also intrigued by your last paragraph. In the original LED fan systems, the lights are just in parallel with the fan motor and DO change their brightness as the voltage to the motor is changed. BUT those fans have only ONE cable. The new RGB and ADDR RGB fans have separate cables for the lighting, as you describe, and power for the lights is completely separate from power for the motor, so there should be NO relationship between fan motor speed and light intensity.

Regarding setting fan options and "curves", remember that, after you set items in BIOS Setup, you MUST use the SAVE and EXIT option to save those settings and use them. Otherwise any setting you change it NOT changed. This does NOT apply if you are using, instead, a fan utility that runs as an app under Windows.

You may be a little confused about two fan header option settings. The MODE specifies the particular method used to adjust fan speed, and the options normally are PWM, Voltage (or DC), or Auto (supposed to detect fan type attached and make this setting by itself). Separately from that you can set a fan PROFILE, which is how your system decides what fan speed it should run. Options here normally include Auto (or Standard) for automatic adjustments based on temperature measurement by sensors, Turbo (or similar) for max speed always, Quiet for slow quiet low cooling, and Custom Curve you can set yourself. Your ability to specify a custom curve should NOT be dependent on what MODE is used to make the fan run at the speed chosen.

Most mobos have two temperature sensors. One is actually built into the CPU chip by its maker and fed out on a chip pin, and this is ALWAYS used to guide the automatic fan control for the CPU_FAN header. It also MAY be used for a related header like CPU_OPT. Then there's always a second sensor built into the mobo at some appropriate spot and used to guide the SYS_FAN or CHA_FAN headers. So these are suited to case ventilation fan management. SOME mobos also add more sensors on specific components of the mobo just in case you intend to dedicate one fan to cooling a particular mobo point. Some also allow you to use the internal CPU temp sensor for SYS_FAN headers if you need to, and a few even leave their SYS_FAN headers using the internal CPU sensor by default. This last is a POOR chioice, I believe, becasue case vntilatin should be based on temps on the mobo, not inside the CPU chip.
 
Cooler Master's MasterFan Pro 120 Air Balance RGB is a full RGB fan but is designed in an odd way:
mf_p_rgb_series_05_00_af120.png

instead of having it's own RGB cable controlling LED color/intensity it just has a switch to determine color(s). and the PWM cable controls the LED power/brightness like older LED versions.

so when the fans speed slows/stops the lights also dim/shutdown.

if you do not like the "breathing mode" that a particular speed curve may produce, i would suggest just settings the fans at a constant speed high enough to produce a good light saturation but low enough to keep fan noise down.
 

divinewarax

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Jul 21, 2018
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510
On the Cooler Master website, the only MasterFan Pro Air Balance fans I can find have NO lighting in them at all. If I look instead for their RGB fans, there are MF and SF series, but none under the Pro name.

I am also intrigued by your last paragraph. In the original LED fan systems, the lights are just in parallel with the fan motor and DO change their brightness as the voltage to the motor is changed. BUT those fans have only ONE cable. The new RGB and ADDR RGB fans have separate cables for the lighting, as you describe, and power for the lights is completely separate from power for the motor, so there should be NO relationship between fan motor speed and light intensity.

Regarding setting fan options and "curves", remember that, after you set items in BIOS Setup, you MUST use the SAVE and EXIT option to save those settings and use them. Otherwise any setting you change it NOT changed. This does NOT apply if you are using, instead, a fan utility that runs as an app under Windows.

You may be a little confused about two fan header option settings. The MODE specifies the particular method used to adjust fan speed, and the options normally are PWM, Voltage (or DC), or Auto (supposed to detect fan type attached and make this setting by itself). Separately from that you can set a fan PROFILE, which is how your system decides what fan speed it should run. Options here normally include Auto (or Standard) for automatic adjustments based on temperature measurement by sensors, Turbo (or similar) for max speed always, Quiet for slow quiet low cooling, and Custom Curve you can set yourself. Your ability to specify a custom curve should NOT be dependent on what MODE is used to make the fan run at the speed chosen.

Most mobos have two temperature sensors. One is actually built into the CPU chip by its maker and fed out on a chip pin, and this is ALWAYS used to guide the automatic fan control for the CPU_FAN header. It also MAY be used for a related header like CPU_OPT. Then there's always a second sensor built into the mobo at some appropriate spot and used to guide the SYS_FAN or CHA_FAN headers. So these are suited to case ventilation fan management. SOME mobos also add more sensors on specific components of the mobo just in case you intend to dedicate one fan to cooling a particular mobo point. Some also allow you to use the internal CPU temp sensor for SYS_FAN headers if you need to, and a few even leave their SYS_FAN headers using the internal CPU sensor by default. This last is a POOR chioice, I believe, becasue case vntilatin should be based on temps on the mobo, not inside the CPU chip.

I have been saving and exiting correctly, yes. The thing is, like I said, I'm using the same BIOS fan curve settings (PWM) and they are plugged into the same headers as I've always had them. I have updated the BIOS in hopes maybe it was something to to with that but to no avail.

Regarding the fans, I apologize for the confusion. They are the MasterFan MF series. The 120 I believe.

Now regarding the BIOS fan settings, when I choose the option other than PWM I have far less control over the fan curves. IIRC the minimum speed is far higher than with the PWM mode. So ever since building the PC I've used PWM. And I had the same fan profiles before AND after it started having this problem. As I stated before I have recently gone in and messed with the fan curves to see if that would help at all. I've tried raising the minimum speed and raising the minimum speed. Nothing has seemed to make a difference. It (the fan) still randomly turns off and when it comes back on it shoots back up to speed. While writing this response I had DiRT Rally 2.0 open in the background and I noticed the fan did it more than it usually would. I've since closed the game and its only happening very infrequently.
 

divinewarax

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Jul 21, 2018
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Cooler Master's MasterFan Pro 120 Air Balance RGB is a full RGB fan but is designed in an odd way:
mf_p_rgb_series_05_00_af120.png

instead of having it's own RGB cable controlling LED color/intensity it just has a switch to determine color(s). and the PWM cable controls the LED power/brightness like older LED versions.

so when the fans speed slows/stops the lights also dim/shutdown.

if you do not like the "breathing mode" that a particular speed curve may produce, i would suggest just settings the fans at a constant speed high enough to produce a good light saturation but low enough to keep fan noise down.

My fans have 2 cables, I'm certain of it. I will disassemble everything after posting this reply to see if mine does have that switch though. And to go back over all the cables to make sure I didn't mess something up. I do remember unscrewing the fan and moving it around while I routed my new RGB cable above it. IIRC I set up the cables and everything the same way it was before though.

The ONE thing more major that I did change other than cleaning up the cable management is I moved the RGB hub that the Cooler Master fans come with from under the bottom of my Hard Drive to directly on the back of the case. Behind the motherboard, on the metal back of the cases. So all the cables are routed differently. The hub is magnetic which is how I was able to do this. Maybe something about having it there messed up some sort of grounding?

Thank you guys for continuing to help me with this!
 
yes, it will probably have an RGB cable; the three settings shown(R, B, RGB) would reflect this.
static Red, static Blue , or externally controlled RGB.

but, like i stated previously it appears that the intensity/brightness is controlled by the PWM power and not the RGB extension. that may even change when set to RGB. the color saturation and brightness could be switched to external RGB control.

test the fan's color options. make sure all are set to RGB and if available, that their RGB cables are all plugged in correctly. then try different fan speeds(0% - 100%) and see how it affects the RGB effects.

i guess the fan hub has PWM and RGB output to the motherboard?
 

divinewarax

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Jul 21, 2018
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yes, it will probably have an RGB cable; the three settings shown(R, B, RGB) would reflect this.
static Red, static Blue , or externally controlled RGB.

but, like i stated previously it appears that the intensity/brightness is controlled by the PWM power and not the RGB extension. that may even change when set to RGB. the color saturation and brightness could be switched to external RGB control.

test the fan's color options. make sure all are set to RGB and if available, that their RGB cables are all plugged in correctly. then try different fan speeds(0% - 100%) and see how it affects the RGB effects.

i guess the fan hub has PWM and RGB output to the motherboard?

So I opened the PC again and they do have the switches and are all set to the RGB mode. I have noticed its not just the back upper fan that will randomly go off then back on, its all three of the fans. I simply cannot find a solution anywhere online and all attempts I've made to find a solution myself just left me with the same. Its starting to really frustrate me. I find myself using the PC less and less because its not only obnoxious but I fear it could be bad.

Rant over. Maybe there is a chance its the PSU? Possibly a bad SATA cable? My theory is that the fans randomly powering off and on is connected to the brightness of the RGB scaling with fan RPM. Both issues seem to have began at the same time.

I'm half tempted to open it again right now and just dig around. Maybe change out some of the cables with extra ones I've got laying around. Thank you to everyone who's stuck around. I know typically a solution would've been found by now. Hopefully soon!
 

divinewarax

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Jul 21, 2018
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Have some new information. My PC cannot stay in a sleep state. It immediately wakes itself back up. This also began around the same time as the fan problems. Was thinking maybe that could narrow down the search for a solution. Going to try using the still-new spare Power Supply. Just trying anything at this point.
 
Have some new information. My PC cannot stay in a sleep state. It immediately wakes itself back up. This also began around the same time as the fan problems.
this is a common issue that arises caused by Window's Power Plan(s).
when USB, PCI-Express or other devices are set a certain way they will cause the system to "awaken" at random times when in sleep or hibernate mode.

in Control Panel > Power Options;
set your power plan's USB settings > USB selective suspend setting to "Disabled".
and set PCI Express > Link State Power Management to "Off".

and see if the issue still arises.
 

divinewarax

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Jul 21, 2018
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I COME BEARING GOOD NEWS. I figured it out! And I can't put into words how good it feels. Thank you to everyone who contributed!

It was AI Suite III. I KID YOU NOT. I simply uninstalled it, restarted my PC and logged in. HWinfo is now reporting fan speeds of 700-800. Nearly TWICE what they used to me on idle, in other words, WHERE I WANTED THEM. They no longer shut off randomly or change brightness. It's over and I'm so glad. :))
 
yeah, Ai Suite will set some odd fan curve profiles in it's default state.

running it's Fan Tuning option sometimes tries to set my fans to a "quiet" mode, giving almost no airflow. and other times sets them all at 100% DC mode.
i imagine it's just flawed in it's current state and sometimes randomly sets it's different built-in speed profiles.

it's nice that it can read individual RPMs for each fan header and show you that in context but it definitely needs to be manually setup each time.