There was quite some controversy about Microsoft's decision to cease support for new processor architectures on Windows 7 and Windows 8.x. The software giant has been communicating for a while now that AMD's Ryzen and Intel's Kaby Lake require Windows 10 and earlier this month the company showed it was serious by cutting off security updates for these processors.
If you're still hell-bent on running a new CPU on an older operating system, you'll be happy to hear that there's now a workaround that enables you to keep using Windows 7 or Windows 8.x.
GitHub user created a patch over here. Use this at your own risk, there's no official Ryzen or Kaby Lake support for these versions of Windows so upgrading to Windows 10 is still the safest bet.