Motherboard boot up behavior when CPU not supported by BIOS

[clarus7]

I have a R680EI motherboard that require a BIOS update to support 13th gen CPU.  I install a 13th gen CPU before BIOS update. At power up, the CPU fan will spin up and then shutdown in less than 2 seconds. I am trying confirm if this is normal behavior because of CPU-BIOS mismatch or it should still boot up to allow BIOS update.

[Jiaszzz_ASUS]

Hello @clarus7 

We apologize for the delayed response due to the recent local holiday.
May I ask if your current usage model is the R680EI-IM-A motherboard?
Could you clarify if this issue occurred right after the PC was built or after some time of use and following any recent changes?
We recommend updating the BIOS and checking again to see if the system can boot correctly.
Additionally, please refer to the user manual to ensure that all hardware is installed properly and the below FAQs if needed:
[AIOT] How do you update BIOS?
[AIOT] How do you fix No Power/No Boot/No Display issues?

Thank you.