Question CPU FAN fail

bde

Member
Mar 15, 2004
191
3
81
Hey guys,
Its been over 2 weeks that I have completed my build, and today upon booting I get the “CPU fan fail” I turned off the pc 2 times and rebooted, still the same. I then turned off the pc and turned off the PS as well and when I rebooted It worked just fine, I did several reboots after that, didnt happen again.It was fine.
You might say well if “If it aint broke don't fix it” true, but I play competitively online and I need to get on at a fixed schedule I cant afford delays or this happening again.
I remember when I booted for the first time, I had a cpu fan fail but that was because I had plugged the kraken Z73 to the AIO header.. and because im a rookie didnt want to fiddle too much with the bios to turn it off, so I switched it to the CPU_FAN header and obviously that solved the issue. Nothing ever happened until today.
Only things I have changed in the bios is the following:
-Fan settings to PWN
-D.O.C.P to the profile1 the pre-available.
-on the top right “EZ system tuning” I changed the gauge icon from white Normal to red Optimal
I dont know what else to change, not a huge overclocking fan, if i can do it and its fail safe, sure
Why not but thats a whole different topic.
Maybe there are other settings I have missed? I understand that
It could be unrelated to the cpu fail.
So all to say what do I have to do for this CPU fan fail error to not happen again or prevent it, Its kind of difficult to determine what caused it since it was only one time.

Thanks


my pc:
Asus Dark Hero
5950x
NZXT kraken Z73 RGB
32GB (4x8GB 3600 14-14-14-34)
1TB NVME Samsung 980 pro m.2 (only as a drive)
Corsair HX1000
Asus ROG 3090
 

mikeymikec

Lifer
May 19, 2011
15,301
5,445
136
I'll start by saying that I know zero about liquid cooling, but I have a fair bit of experience with Asus motherboards and CPU fan speed detection. In my experience, what commonly (but not with all systems) happens when the system is booted is that the fan will start and stop a few times before starting up in earnest.

When the CPU fan fail message appears, what sometimes is the case is that the fan hasn't started up in earnest until a second or two after the message appears.

The first thing I'd do in your shoes is visually confirm (or confirm by feeling airflow from the fan if possible) that the fan is working at the point during boot when the message typically appears, and after a few checks you'll know whether the message is bogus or not.

If the message is bogus, you can tell the BIOS to ignore the CPU fan speed. It's not a setting I like to use as it strikes me very much like 'the boy who cried wolf' (ie. you've checked various times and found that the error is incorrectly displayed, then set BIOS to ignore the fan speed, then the CPU fan truly dies), but I've seen it often enough in various Asus systems to know that it's not definitely a sign of CPU fan failure.
 
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coercitiv

Diamond Member
Jan 24, 2014
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I remember when I booted for the first time, I had a cpu fan fail but that was because I had plugged the kraken Z73 to the AIO header.. and because im a rookie didnt want to fiddle too much with the bios to turn it off, so I switched it to the CPU_FAN header and obviously that solved the
-Fan settings to PWN
my pc:
Asus Dark Hero
NZXT kraken Z73 RGB
I suggest you take another look at your Kraken Z73 manual, specifically the installation instructions and the roles of each cable. Here's a quick explanation bellow, and what I think you should do to avoid error messages in the future.

Your AIO cooler has a special way of controlling the fans: they are powered directly from your pump housing. The housing is powered using a SATA cable, and then you have a special 4-PIN PWM cable with multiple heads that you connect to your AIO fans.

The cable you have connected to the CPU_FAN header is actually used by the pump, not the fans. This cable is only used to let the motherboard know about the speed of the pump, not to power the pump - this is important as it means your motherboard does not control the pump speed at all. See this slide from the manual bellow, also notice the NOTE which is of particular interest considering your problem.
You may need to disable fan-fail warning within the motherboard BIOS if CPU_FAN is unused.
1639578238441.png

So here's what I think is happening:
  • you connected the 3-PIN pump cable to the CPU_FAN header, and also switched the control mode to PWM thinking you'll control the PWM fans that come with your Kraken AIO.
  • the ASUS board does not receive proper electrical feedback trough this connection, since it's both set to PWM and receiving speed information from the pump, not the fans.
What you should do:
  • change the fan control from PWM to DC, as there's no PWM control here
  • disable the CPU Fan Speed monitoring on your motherboard (that's probably a setting called CPU Fan Speed which can be set to Ignore), alternatively you can try to set CPU Fan Speed Low Limit to the lowest speed possible such as 200RPM
Optionally, and maybe better to do if you're willing to open the system, you can move the cable to the AIO_PUMP header and disable CPU Fan Speed monitoring. The AIO_PUMP header is right next to the CPU one, see bellow:

1639580003600.png
 
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bde

Member
Mar 15, 2004
191
3
81
I'll start by saying that I know zero about liquid cooling, but I have a fair bit of experience with Asus motherboards and CPU fan speed detection. In my experience, what commonly (but not with all systems) happens when the system is booted is that the fan will start and stop a few times before starting up in earnest.

When the CPU fan fail message appears, what sometimes is the case is that the fan hasn't started up in earnest until a second or two after the message appears.

The first thing I'd do in your shoes is visually confirm (or confirm by feeling airflow from the fan if possible) that the fan is working at the point during boot when the message typically appears, and after a few checks you'll know whether the message is bogus or not.

If the message is bogus, you can tell the BIOS to ignore the CPU fan speed. It's not a setting I like to use as it strikes me very much like 'the boy who cried wolf' (ie. you've checked various times and found that the error is incorrectly displayed, then set BIOS to ignore the fan speed, then the CPU fan truly dies), but I've seen it often enough in various Asus systems to know that it's not definitely a sign of CPU fan failure.
Thanks I appreciate your feedback hopefully it will not happen again, I did hear the fans running at full speed specially when I reverted the bios settings back to default
 

bde

Member
Mar 15, 2004
191
3
81
I suggest you take another look at your Kraken Z73 manual, specifically the installation instructions and the roles of each cable. Here's a quick explanation bellow, and what I think you should do to avoid error messages in the future.

Your AIO cooler has a special way of controlling the fans: they are powered directly from your pump housing. The housing is powered using a SATA cable, and then you have a special 4-PIN PWM cable with multiple heads that you connect to your AIO fans.

The cable you have connected to the CPU_FAN header is actually used by the pump, not the fans. This cable is only used to let the motherboard know about the speed of the pump, not to power the pump - this is important as it means your motherboard does not control the pump speed at all. See this slide from the manual bellow, also notice the NOTE which is of particular interest considering your problem.


So here's what I think is happening:
  • you connected the 3-PIN pump cable to the CPU_FAN header, and also switched the control mode to PWM thinking you'll control the PWM fans that come with your Kraken AIO.
  • the ASUS board does not receive proper electrical feedback trough this connection, since it's both set to PWM and receiving speed information from the pump, not the fans.
What you should do:
  • change the fan control from PWM to DC, as there's no PWM control here
  • disable the CPU Fan Speed monitoring on your motherboard (that's probably a setting called CPU Fan Speed which can be set to Ignore), alternatively you can try to set CPU Fan Speed Low Limit to the lowest speed possible such as 200RPM
Optionally, and maybe better to do if you're willing to open the system, you can move the cable to the AIO_PUMP header and disable CPU Fan Speed monitoring. The AIO_PUMP header is right next to the CPU one, see bellow:

View attachment 54402
I suggest you take another look at your Kraken Z73 manual, specifically the installation instructions and the roles of each cable. Here's a quick explanation bellow, and what I think you should do to avoid error messages in the future.

Your AIO cooler has a special way of controlling the fans: they are powered directly from your pump housing. The housing is powered using a SATA cable, and then you have a special 4-PIN PWM cable with multiple heads that you connect to your AIO fans.

The cable you have connected to the CPU_FAN header is actually used by the pump, not the fans. This cable is only used to let the motherboard know about the speed of the pump, not to power the pump - this is important as it means your motherboard does not control the pump speed at all. See this slide from the manual bellow, also notice the NOTE which is of particular interest considering your problem.


So here's what I think is happening:
  • you connected the 3-PIN pump cable to the CPU_FAN header, and also switched the control mode to PWM thinking you'll control the PWM fans that come with your Kraken AIO.
  • the ASUS board does not receive proper electrical feedback trough this connection, since it's both set to PWM and receiving speed information from the pump, not the fans.
What you should do:
  • change the fan control from PWM to DC, as there's no PWM control here
  • disable the CPU Fan Speed monitoring on your motherboard (that's probably a setting called CPU Fan Speed which can be set to Ignore), alternatively you can try to set CPU Fan Speed Low Limit to the lowest speed possible such as 200RPM
Optionally, and maybe better to do if you're willing to open the system, you can move the cable to the AIO_PUMP header and disable CPU Fan Speed monitoring. The AIO_PUMP header is right next to the CPU one, see bellow:

View attachment 54402
Thanks…you bring interesting points, I will try it and let you know how it goes. I can swear that I went over the guides a multiple times but I can see that my perception of what the AIO_PUMP header actually does was wrong…I am considering your last comment as well to open the case and switch the headers again… last time I gently pulled the wires knowing that I shouldn't have cause I coulnt properly grip 3 pin with my fat fingers but we’ll see.
Meanwhile ill ask you this, Right now i have the two left fan headers used. On the CPU_OPT I plugged in my case’s fan header hub which has 1 fan on the back of the case air outflow and 2 fans at the bottom air inflow. The CPU_FAN has the pump’s 3 pin header as we discussed earlier and the 3 fans of the pump attached to the radiator are connected to the headers coming out of the pump as per the instructions. AIO_PUMP empty as you know. What do you ultimately suggest I use out of the 3 headers?
thanks for your feedback.
 
Last edited:

coercitiv

Diamond Member
Jan 24, 2014
4,910
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136
Right now i have the two left fan headers used. On the CPU_OPT I plugged in my case’s fan header hub which has 1 fan on the back of the case air outflow and 2 fans at the bottom air inflow. The CPU_FAN has the pump’s 3 pin header as we discussed earlier and the 3 fans of the pump attached to the radiator are connected to the headers coming out of the pump as per the instructions. AIO_PUMP empty as you know. What do you ultimately suggest I use out of the 3 headers?
You can probably leave everything as is right now and just try to adjust BIOS settings so that the warning doesn't appear anymore, especially if you're having difficulty removing the cables from their current position.
 
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bde

Member
Mar 15, 2004
191
3
81
You can probably leave everything as is right now and just try to adjust BIOS settings so that the warning doesn't appear anymore, especially if you're having difficulty removing the cables from their current position.
Sorry I think I explained it wrong, the warning stopped appearing ever since I moved the Kraken z73 pump 3 pin from the AIO_PUMP to CPU_FAN...I did that the first day that I built the system. 2 week ago and the system was working just fine, no warnings what so ever.... only now after 2 weeks there was a one time only FAN FAIL error... and that was just one time only....after turning off the Pwer supply and on and booted the pc, it never happened again... I just want prevent it
*edited* I tried changing from PWN to DC and the fan goes nuts and its already set to the lowest 200RPM.... so left it as is for now... what do you suggest for that? or I should ask what is the most "ideal" setup with this type of pump?
 
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Markfw

CPU Moderator, VC&G Moderator, Elite Member
Super Moderator
May 16, 2002
22,912
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Sorry I think I explained it wrong, the warning stopped appearing ever since I moved the Kraken z73 pump 3 pin from the AIO_PUMP to CPU_FAN...I did that the first day that I built the system. 2 week ago and the system was working just fine, no warnings what so ever.... only now after 2 weeks there was a one time only FAN FAIL error... and that was just one time only....after turning off the Pwer supply and on and booted the pc, it never happened again... I just want prevent it
I have had that problem also. Just put ANY 4 pin fan on the "cpu fan" header, and all others anywhere you want. Then you never get the error. In my case, I used a case fan !
 

bde

Member
Mar 15, 2004
191
3
81
I have had that problem also. Just put ANY 4 pin fan on the "cpu fan" header, and all others anywhere you want. Then you never get the error. In my case, I used a case fan !
lol right? hassle free... I mean it did say in the manual so why not :)
 

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