Hi, my name is Kelly, and I'm an independent consultant and I'm here to help.
I'm sorry to hear that you're having trouble accessing your encrypted files after your motherboard died. Here are a few things you can try to regain access to your files:
Try logging in with the same user account: If you can still access the Windows installation on the original hard drive, try logging in with the same user account that was used to encrypt the files. This may allow you to access the encrypted files.
Use your EFS recovery agent: If you set up an EFS recovery agent when you encrypted the files, you may be able to use it to access the encrypted files. Check your EFS recovery agent certificate to see if you can use it to decrypt the files.
Decrypt the files using a backup of your EFS certificate: If you have a backup of your EFS certificate, you may be able to use it to decrypt the files. To do this, you'll need to import the EFS certificate into the certificate store of the computer you're using to access the encrypted files.
Contact a data recovery specialist: If you're unable to access your encrypted files using the above methods, you may need to contact a data recovery specialist who has experience with EFS encryption. They may be able to help you recover your encrypted files.
Note that EFS encryption is tied to the user account that encrypted the files and the specific hardware that was used to perform the encryption. If you're unable to access the encrypted files using any of the above methods, it may not be possible to recover them.