Cpu F1 fan Error only on first boot

[mr griffin]

Hi I recently built a pc for one of my mates, it has a strange issue that I can't figure out.
First boot in the mornings it always comes up with a F1 cpu fan error??
After that it seems to be OK but will randomly do it other times too but always in the morning. Can't understand why.
Does anyone have any idea why this is happening?
Specs below

Asus x570 Crosshair v11 hero wifi
5900x
64gb corsair 3600 ram
1000w bequiet psu
2 x 2tb segate firecuda 530s
Bequiet dark rock pro

 

[mr griffin]

Is there a minimum or a warning speed set for the CPU fan in the bios?

Yes you can disable f1 error and put it to ignore, but it shouldn't be doing it, it always does it first boot up of the day and then it's pretty much OK so makes no sense

 

[mr griffin]

Is there a fan plugged in to the actual CPU fan header, and if so is it spinning up when the system first powers up?

Yeah I had the Splitter on the Dark rock pro 4 plugged into the cpu fan header, and now have also taken the Splitter off and plugged one into the cpu fan header and the other into the second cpu fan header, so both are being used, both fans are also spinning. That's why I just can't understand why I would get the fan error on this machine every morning.

 

[mr griffin]

Assuming the fan is actually working as intended?

Yes it's spinning up fan, it's pwm and you can see it going faster and slower as the cpu is stressed on something like cinebench