Assuming that your "old" 1 TB SSD from the Foxconn build contains a viable Win 7 OS, i.e., it's non-defective, bootable, and functions problem-free, it's conceivable that you can install that disk in your new build and it will boot & function just fine in the new system.
Please understand that the information I'm about to provide is based on our rather extensive experience re our attempts involving the transfer of a considerable number of systems from one PC to another PC.
As a general proposition we have found the chances of a successful transfer increase when...
1. Both the old & new PCs are non-OEM machines, and,
2. Both PCs are either Intel-based or AMD-based systems.
However, understand the above are not "hard & fast" rules. We've successfully transferred systems in spite of the above "criteria" not being met, especially in situations where the old PC is a OEM machine but the new PC is a non-OEM machine, i.e., self or custom built with non-proprietary components.
Obviously there are no guarantees that the transfer will be successful but it's worth a shot. There's little to lose since you always retain the option of returning the original boot drive that was installed in the Gigabyte system.
Now I'm sure you understand that if you attempt this transfer operation you would FIRST uninstall the present boot drive (and any other drive) from the "new" PC so that the ONLY installed drive would be the drive to be transferred, right?
So if by undertaking this transfer you're fortunate enough to gain a bootable, functional system as a result, you will, of course have all your programs, personal data, etc. available without going through that rather onerous task of installing a new system.
Obviously you may have to install different drivers of one type or another in the new system but of course these will be available from your new motherboard's driver installation CD. And you may be pleasantly surprised at Windows (Microsoft's) ability to pick up & install whatever drivers are necessary for your new installation without user intervention (especially if the OS is Win 10).
NOW...
IF YOU DO DECIDE TO UNDERTAKE THIS TRANSFER ATTEMPT WE STRONGLY SUGGEST THAT BEFORE DOING SO YOU CLONE THE CONTENTS OF THE DRIVE TO BE TRANSFERRED. SHOULD THE TRANSFER OPERATION FAIL, THE NEW SYSTEM MIGHT - REPEAT, MIGHT - MODIFY THE DRIVE'S CURRENT OS DURING THE TRANSFER OPERATION IN SUCH A FASHION THAT THE "OLD" DRIVE'S OS COULD BE ADVERSELY AFFECTED, RESULTING IN AN UNBOOTABLE OS IF & WHEN THE DRIVE IS RE:INSTALLED BACK IN THE "OLD" PC. WE HAVE EXPERIENCED THIS SITUATION IN EXTREMELY RARE CASES. HOWEVER, THE DRIVE'S NON-OS DATA SHOULD NOT BE AFFECTED; AT LEAST WE'VE NEVER RUN INTO THAT SITUATION IN THE EVENT OF A FAILED TRANSFER ATTEMPT. OBVIOUSLY THIS CAUTIONARY NOTE IS APPLICABLE ONLY IF YOUR INTENTION IS TO RETURN THE TRANSFERRED DRIVE BACK TO ITS "OLD HOME". Capiche?
We've undertaken successful transfers of the type described many times and we nearly always undertake this option when circumstances permit, i.e. the above criteria I mentioned above are met.
Assuming the transfer operation is successful there shouldn't be an activation problem in this situation. (I'm assuming, of course, that your Gigabyte system is activated.) But one never knows about these things at the outset of this type of transfer operation. The whole MS "activation" process is something of a mystery and we find time & time again it frequently differs in process from system to system.
If you do decide to effect this transfer as described above please let us know if it was successful or not.