There's no Intel USB3 win7 drivers for the 300 series chipset. You would need some third party pcie usb3 card that has drivers...
There's a whole thread over here https://forums.mydigitallife.net/th...-kabylake-coffelake-ryzen-threadripper.76335/ That can help you get Windows 7 on a newer pc
At the OP you already posted you used Win 7 image updater, it's the link Joe C gave... The problem with that project is that the dev uses drivers which often don't work, when used win-raid provided drivers it mostly works.
I noticed that. I still haven't got win7 on this desktop even after buying a generic usb 2.0 pci expreas card and installing it. Still no results
I purchased another card and that got windows 7 on the desktop, but I can't install intel usb 3.0 drivers which means most of my ports don't work. Sadly my only option id to use windows 8.1....I wish i could return this machine. Oh well. Thanks for your help everyone.