Wait so let me get this straight. You are upgrading from a 4790k to a 7700k and are wondering if you can still use the same boot ssd.
Here is something I found - looks like you might be out of luck if you are also using a new motherboard.
https://www.google.com/amp/s/www.howtogeek.com/239815/why-cant-you-move-a-windows-installation-to-another-computer/amp/
But, you can get a cheap external hdd, back up all of your files, and do a clean install of windows by clearing all of your storage devices and reinstalling.
Here is a 1tb external hard drive but they sell ones with less storage if you don't have a terabyte of data on your pic.
https://m.newegg.com/products/N82E16822178744?ignorebbr=true&nm_mc=OTC-Froogle-Mobile&cm_mmc=OTC-Froogle-Mobile-_-Hard+Drives+-+Portable+External-_-Seagate-_-22178744&gclid=Cj0KEQjw1ufKBRDYrqLzrY3dy88BEiQAPI_r4X0YOroLA21RtH2ou9raV1XzOidy3AEGuvVOMGgkHaYaAmQv8P8HAQ
Hope this helps.
-LC