[SOLVED] Brand new System. CPU Fan not spinning

[siflvio]

I bought today a brand new system.
I put everything together.
after i start the system the CPU Fan is spinning short and then stops. now i got the message "no CPU FAN DETECTED".
I checked all the BIOS settings but found nothing wrong. I tested to put the cpu fan in the CHA_FAN and it runs.
So what can be the problem?
rather the mainboard or cpu? or Power supply? any ideas? thx so far.
AMD Ryzen 7 3700X
ASUS ROG Strix B450-F Gaming
Corsair RM750x

 

[Grobe]

Does the fan behave the same way if you connect it to another fan connector?

Have you checked that the correct fan connector is used?

Have you tried to mount the fan connector to a wrong kind of plug?

 

[siflvio]

I had to update the bios, now i'ts working. thx for your reply.