Depends upon the original Windows 10 purchase option. Did you buy a full retail copy (either in box or downloaded)? Or did it come installed in a computer that you bought?
If the full retail copy, you have the right to transfer it to a different computer (a new motherboard but same box and HDD in your situation). Contact Microsnot, as Dave suggest, for activation.
If the Windows came installed in a computer, it is forever tied to the motherboard of that computer. Only an identical motherboard model will work with that manufacturer's copy of Windows. You will have to buy a new retail copy of Windows.
Long ago I learned about Microsh*t. I bought a computer with DOS from largest electronics company on planet. They upgraded me for free to Win95. Then that company dumped all personal computer business. I bought a retail upgrade box for Win98SE. Would not install. Microsnot said to contact the computer maker/seller. I was out of luck.