new hardware

Hello John,

Since your Windows 10 license was OEM, it is permanently tied to the motherboard it was originally activated on. When your old mobo died, the license died with it because Microsoft considers a motherboard replacement to be a completely new computer. Your cloned drive boots up perfectly because all your files and the OS are still there, but the Microsoft activation servers see the new hardware ID and will reject the old OEM key you pulled from the registry.

Regarding the Windows 7 key on your case, Microsoft officially closed the loophole that allowed old Windows 7 and 8 keys to activate Windows 10 back in late 2023. That sticker will not help you get activated now.

The next step is to purchase a new retail Windows 10 or Windows 11 license to activate your system on this new hardware. You can buy a digital license directly through the activation settings on your PC, which will route you to the Microsoft Store.

there is a key on the case for windows 7

Because the original Windows 10 Pro was an OEM installation that was digitally activated by the seller, the license is tied to the original motherboard. After replacing the motherboard, that OEM license generally cannot be transferred, which is why Windows now needs reactivation.

Next steps:

1. Try reactivating with the existing key:
   • Select Start > Settings > Update & Security > Activation.
   • Select Change product key.
   • Enter the 25-character product key that was found in the registry and follow the prompts.
   • If activation succeeds, nothing more is needed.
2. If activation fails with that key:
   • OEM keys are usually not valid after a motherboard change unless the replacement was done by the original hardware manufacturer (OEM). In that case, activation should happen automatically, or the OEM may have provided a Certificate of Authenticity (COA) card with a product key:
     • If there is a COA label or card with a 25-character key (possibly under a gray scratch-off coating), use that key:
       1. Gently scratch off the gray coating if present.
       2. Go to Start > Settings > Update & Security > Activation.
       3. Select Change product key, enter the COA key, and complete activation.
3. If there is no valid COA key and the existing key will not activate:
   • The OEM license from the original motherboard cannot be reused on the new hardware.
   • A new Windows 10 Pro product key or license must be purchased and then entered via Settings > Update & Security > Activation > Change product key.

If the PC was purchased pre-owned or refurbished, and a COA is present on the case, that COA key is the one that should be used for activation.

References:

• Why can't I activate Windows?
• Activate Windows
• Unable to use troubleshooter for windows activation - Microsoft Q&A
• windows 10 pro . - Microsoft Q&A