[SOLVED] Cpu fan stops spinning after some time and after pc wakes from sleep mode

osamaaljamry23

Prominent
Jul 27, 2018
5
0
510
0
I recently built my first pc and noticed this problem, that the cpu fan spins fine after powering on the pc but stops spinning after some time. Also whenever I wake the pc from sleep mode the fan starts to spin for several seconds then stops until the next restart or shutdown. I checked the bios settings and the fan’s settings are all fine and exactly like my friend’s settings (whose fan doesn’t have any problems). I also triple checked the cables and everything seems correct. Is this normal? And how can I let it spin regularly regardless?

Nzxt h500 case
Noctua nh-u14s fan
I7-9700k 8 cores
gigabyte z390 aorus pro wifi
 
Within the Custom curve option, try setting higher than 27%. IF the next-higher point on the curve is also only 27%, raise that one, too. Try using 50% to start. If that eliminates the problem, experiment with reducing that setting until you re-create the problem. Then you'll know how low is too low.
 
Reactions: digitalgriffin

pilotsh

Honorable
May 1, 2014
100
2
10,695
2
Some MB's have two fan controllers, one always on and one dynamic. Double check the MOBO manual and triple check you have plugged the CPU cooling wires/plug into the correct spots on the motherboard.

Also, if you are worried, I would recommending getting a CPU temperature monitor and see what temperature the CPU is at when the fan stops. You said the fan does not restart until a reboot, I would also check what the temperature of the CPU is just before you reboot, and also, has the system ever shutdown/crashed (BSOD) after it running for a period of time?
 

osamaaljamry23

Prominent
Jul 27, 2018
5
0
510
0
Some MB's have two fan controllers, one always on and one dynamic. Double check the MOBO manual and triple check you have plugged the CPU cooling wires/plug into the correct spots on the motherboard.

Also, if you are worried, I would recommending getting a CPU temperature monitor and see what temperature the CPU is at when the fan stops. You said the fan does not restart until a reboot, I would also check what the temperature of the CPU is just before you reboot, and also, has the system ever shutdown/crashed (BSOD) after it running for a period of time?
No it hasn’t crashed yet as I didn’t let the cpu temperature exceed 60 celsius. I have a temperature monitor but it’s still annoying knowing that your fan doesn’t work properly and you can’t figure out whats wrong. I rechecked the wires again and I’m 100% sure they’re plugged in their right spots.
 

pilotsh

Honorable
May 1, 2014
100
2
10,695
2
No it hasn’t crashed yet as I didn’t let the cpu temperature exceed 60 celsius. I have a temperature monitor but it’s still annoying knowing that your fan doesn’t work properly and you can’t figure out whats wrong. I rechecked the wires again and I’m 100% sure they’re plugged in their right spots.
I would run the computer normally, and if the CPU hits 80c and the fan doesn't click in, something is definitely wrong.
But it also sounds like you know something is already wrong, as you are comparing it to another identical fan.
I would say if you are sure something is wrong, take parts back for a replacement under warranty. I would start with the CPU/fan package.
 
Start with knowing what is "normal". On almost all mobos, when the system boots up (or wakens from "sleep") the mobo headers first tell ALL the fans to start up at full speed, so be SURE they start. After a short time (5 to 15 sec) they get a reading on actual temperatures from sensors and slow down the fans to whatever is needed. If the temperatures remain low (often at low workloads) the fans will stay slow or get even slower until rising temp measurements call for more cooling.

Now, all of these systems have settings for what fan speeds will be required for what temperatures are measured. For the CPU cooler, the temperature to be used is the sensor inside the CPU chip. The mobo CPU_FAN header is always tied to this sensor, so that is why you MUST connect the CPU cooling fan to the CPU_FAN header. Then, on this and almost all other headers, you have a choice in BIOS Setup for how the fan speed control is done. The most common and generally best choice is the "Normal" or "Standard" option. In this a set of pre-programmed values is used for the automatic controls. I suspect that is what you are using, but maybe not. There usually are two fixed-speed settings: Turbo or Full Speed, and Quiet or reduced speed. Fourth common setting is "Custom" or "Manual". With this option you do get automatic control based on measured temperature, but YOU get to set the graph of fan speed versus measured temperature, rather than using the pre-progammed values. If you use this and set the minimum speed at lowest temperature too low, the fan may stall and fail to re-start until the temperature rises significantly and calls for higher fan speed. (Is this what you did - you said you copied all your friend's settings?) Alternatively, even if you are using the "Standard" setting, it is possible that the pre-programmed minimum speed in their settings is too low and allows the fan to stall. In either case, the solution is to choose the Custom option and set the lowest fan speed at the lowest temperature to higher speed. That way the fan will never be told to run too slow and risk stalling. If you make any changes like this, remember to SAVE and EXIT from there so your new settings are preserved.
 

osamaaljamry23

Prominent
Jul 27, 2018
5
0
510
0
Start with knowing what is "normal". On almost all mobos, when the system boots up (or wakens from "sleep") the mobo headers first tell ALL the fans to start up at full speed, so be SURE they start. After a short time (5 to 15 sec) they get a reading on actual temperatures from sensors and slow down the fans to whatever is needed. If the temperatures remain low (often at low workloads) the fans will stay slow or get even slower until rising temp measurements call for more cooling.

Now, all of these systems have settings for what fan speeds will be required for what temperatures are measured. For the CPU cooler, the temperature to be used is the sensor inside the CPU chip. The mobo CPU_FAN header is always tied to this sensor, so that is why you MUST connect the CPU cooling fan to the CPU_FAN header. Then, on this and almost all other headers, you have a choice in BIOS Setup for how the fan speed control is done. The most common and generally best choice is the "Normal" or "Standard" option. In this a set of pre-programmed values is used for the automatic controls. I suspect that is what you are using, but maybe not. There usually are two fixed-speed settings: Turbo or Full Speed, and Quiet or reduced speed. Fourth common setting is "Custom" or "Manual". With this option you do get automatic control based on measured temperature, but YOU get to set the graph of fan speed versus measured temperature, rather than using the pre-progammed values. If you use this and set the minimum speed at lowest temperature too low, the fan may stall and fail to re-start until the temperature rises significantly and calls for higher fan speed. (Is this what you did - you said you copied all your friend's settings?) Alternatively, even if you are using the "Standard" setting, it is possible that the pre-programmed minimum speed in their settings is too low and allows the fan to stall. In either case, the solution is to choose the Custom option and set the lowest fan speed at the lowest temperature to higher speed. That way the fan will never be told to run too slow and risk stalling. If you make any changes like this, remember to SAVE and EXIT from there so your new settings are preserved.
I tried everything listed in the bios setup and didn’t get a result it’s always not spinning after waking up. The only setting that didn’t was “Full speed” but I don’t want to keep the fan spinning at full speed all the time because it’s unnecessary. I also tried the custom option, 27% of the full fan speed to be triggered when it hits 4 celsius or higher (which should mean this is the lowest fan speed) but it still didn’t work after waking from sleep.
 
Within the Custom curve option, try setting higher than 27%. IF the next-higher point on the curve is also only 27%, raise that one, too. Try using 50% to start. If that eliminates the problem, experiment with reducing that setting until you re-create the problem. Then you'll know how low is too low.
 
Reactions: digitalgriffin

digitalgriffin

Distinguished
Jan 29, 2008
940
198
19,190
20
Sometimes when I use fan tuning software (like FanXPert by ASUS) it will lower the voltage to what it thinks is starting voltage. However sometimes this is an inaccurate reading. Sometimes the fans in question will require near full voltage to start back up again. So while the motherboard controller thinks it should be running at 500 RPM @ 7 Volts, the fan is stuck at 0 RPM @ 7 Volts. This is especially true as fans age and variable voltage is used instead of 4 pin PWM. Ball bearing and mag lev bearing fans have less an issue here because they require such little current to start moving. Stall current (when the fan isn't moving) is considerably higher, and can cause voltage sag and the fan not to move until it's overcome.) These MB vendors need to re-validate the start voltage every month of so, making sure the fan is at 0 RPM before testing.

So I would see if you have a similar utility or BIOS setting and put the fans on full and see what happens after it goes to sleep, then wakes back up. If the fan starts, you'll need to manually recalibrate your fan curves like I did.
 
Last edited:

osamaaljamry23

Prominent
Jul 27, 2018
5
0
510
0
Within the Custom curve option, try setting higher than 27%. IF the next-higher point on the curve is also only 27%, raise that one, too. Try using 50% to start. If that eliminates the problem, experiment with reducing that setting until you re-create the problem. Then you'll know how low is too low.
This worked, thanks alot. Is this a common problem?
 
You're welcome, and thanks for Best Answer. Not common, but not rare either. I think it happens more often with 140 mm fans because they are designed to push more air at any speed, so they tend to run slower than other fans for the same signal output from a fan header. Thus it is more likely with them that the signal set according the pre-programmed fan control parameters for other fan sizes might be too low and allow the fan to stall. Using the custom fan curve option to raise the minimum fan speed is a good solution.
 
Reactions: pilotsh

ASK THE COMMUNITY

TRENDING THREADS