SUCCESS !!!!Ok so I did the obvious thing and dld a small linux iso and followed the instructions for formatting the disk, using a 3rd party app I formatted it in FAT32. Turns out my assumption that FAT and exFAT were the same was wrong, but this was in some way led by windows 10s formatting options. In my case it the USB was formatted to MBR FAT32 and it worked fine. Undervolting unlocked !!!Thanks for your input guys. Wish me luck   
Hi guys, I was studiously following this to enable undervolting on my Dell xps 9700.I know this probably a touchy subject on this forum so please just take as context for the usb boot requirement. [URL] am stuck at the last hurdle I can't get it to boot into the USB.It's a usb stick with type c and it's been converted to GUID and formatted etc.I have obviously turned of secure boot in the BIOS and allowed booting from thunderbolt. In the BIOS there are fields to add boot options but you cant navigate to the usb drive. It just has these weird 4 options for recovery etc. I have tried disabling other boot options and setting a boot option for EFI\BOOT\bootx64.efi but this just boots into windows. Any ideas?
Boot from USB