Gigabyte Z370 AORUS Gaming 5 Motherboard with i7-8700 Processor. In machine now Gigabyte Z97X (which has failed) and I7-4790K Processor, (4th Generation) OS Windows 7
You need Win 10.
Even if it did theoretically support Win 7, you'd need to do a full reinstall anyway.
So you might as well go with Win 10.
In answer to your question, Yes.How to do a CLEAN installation of Windows 10