CPU cooler turns on then turns off, but computer still running

[john_minton]

Hi,
I just finished building my PC and its up and running. However sometimes on startup the CPU fan fails to turn on so I have to spin it manually, then it starts spinning on its own(something like an old 1900's car). And often maybe once every 5-10 minutes the fan stops again so I have to rotate it manually then it starts spinning on its own. Sometimes after one try it still fails to start so I have to do it several times.
No clue whats causing this, everything is plugged in the right way.
The CPU cooler is also brand new.


SPECS:
Intel i5-8600k
Corsair Vengeance 16gb ddr4 3000mhz
Gigabyte z370 HD3P
Master Cooler Hyper 212 EVO
Samsung 960 evo 500GB
EVGA 500b PSU
No GPU

 

[DanKem06]

Well at startup it's normal for the fans to spin up then slow down but not stop. You should have more than one header for the cpu on your motherboard. Try another header, if the same thing occurs then try another cooler. If that isnt possible can you easily take it back? Can you boot into bios and see fan speeds?

 

[john_minton]

Well at startup it's normal for the fans to spin up then slow down but not stop. You should have more than one header for the cpu on your motherboard. Try another header, if the same thing occurs then try another cooler. If that isnt possible can you easily take it back? Can you boot into bios and see fan speeds?

This usually happens when I'm playing games. When running a game it happens every 20-30 seconds but when on YouTube it almost never happens.

 

[SkyNetRising]

Go into BIOS and set minimum CPU fan speed to a higher value.

I had similar problem with Gigabyte z370 D3.
One of system PWM fans would not start spinning. Had to increase minimum fan speed.

 

[john_minton]

Go into BIOS and set minimum CPU fan speed to a higher value.

I had similar problem with Gigabyte z370 D3.
One of system PWM fans would not start spinning. Had to increase minimum fan speed.

How do you change the minimum fan speed? Sorry, new to Windows and PC's. Just recently migrated from macs haha.

 

[SkyNetRising]

Go into BIOS and find Smart Fan settings section.

 

[john_minton]

Go into BIOS and find Smart Fan settings section.

I did that and didn't work even if all were at 60%. The fan still turns off.

 

[SkyNetRising]

Try more.
What happens at 80% , 100% ?

 

[john_minton]

at 80% it spins up, then suddenly stops, then turns back on, then stops and repeats. But in the fan I can hear some clicky noise from the fan