None of the pre-made Microsoft distributions of Windows 7 were ever updated to support booting from USB 3.0.  You will need to prepare a custom boot drive and use an ISO, or prepare a custom install image, with the USB 3.0 drivers. Video here: [URL] Drivers here [URL]  
I am trying to recover and I did once, but now I can't get passed missing drivers. I have a dvd with drivers, I'm booting from USB. It doesn't accept any of the USB 3 drivers on the USB. What can I try to reinstall win7?     . TOS76> 
Win7 recovery Dell E6430s no drivers.