Yes, you can perform a clean installation of Windows 8.1 and keep your Steam games intact.
Yes, you can perform a clean installation of Windows 8.1 and keep your Steam games intact.
Only the SSD will be affected; for extra security, disconnect the HDD first and then reinstall Windows.
Save your games on an external drive > set up Windows 8 > launch Steam > transfer your games back to the Steam apps common folder > when you attempt another installation, it will automatically find the required files and perform a quick check plus updates. That's the process. Transferring manually by copying or pasting folders is quicker than relying on Steam's backup and restore feature.