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#101
That will only work for a year.How did you install Windows 8.1 on your SSD? Can't you access the same installation source? If not, and if you have a legit Win 8.1 license key, you can download the Windows 8.1 software from a torrent - it's the license that's legally requires to access and use the software, and it's legal to download software for which you own a license to use.
You can also try contacting Microsoft support, and asking them to deactivate the previous hardware association for your license, and activating it with the new one.
Support for Microsoft product activation problems
Typically, changing the mobo will require you to re-install Windows 8.1, and then upgrade to Windows 10.