Hi ,
I'm Dyari. Thanks for reaching out. I will be happy to assist you in this regard.
The process of activating Windows after a hardware change depends on the type of license you possess.
If your computer came preinstalled with an OEM license, the license was tied to your old motherboard and could not be transferred. You will need a new one for your new computer.
If you bought the product key separately and it was a retail key, try to reactivate it:
Settings > System > Activation > Change Product Key and enter the key that you have.
If it is a digital license linked to your Microsoft account, it should activate Windows automatically after signing in with your Microsoft account.
If it did not work, try to troubleshoot it by going to Start >System > Activation > Troubleshoot.
Reactivating Windows after a hardware change:
Please let me know if you need further assistance.