Installing Windows 10 on Dell XPS 12
I tried to install Windows 8.1 as well as other version of Windows on my Dell XPS 12 in recent months and failed repeatedly. I couldn't get the USB thumb drive to be recognized. Early on I found Mike Taulty's post that sounded exactly like my problem. I've been a reader of Mike's stuff for a long time so I thought for sure this would fix my issue. I followed the instruction (or so I thought), and it didn't work for me. Well, it turns out, I did not follow his instructions. The short version of Mike's post is that with Windows 8 and the XPS 12 specifically there's all kinds of new stuff going on with UEFI and Secure Boot, but the core problem is your thumb drive will not be recognized by UEFI if it's not FAT32. I formatted my thumb drive as FAT32 and then ran it through my trusty install of Windows USB/DVD Download Tool to get a bootable USB of my Windows media. Well, it turns out this tool reformats the drive for you at the beginning of it's routine and does it was NTFS (not FAT32).
Here's what I did to get my USB Thumb Drive primed for installation of Windows 10 on my Dell XPS 12:
1) Open a command prompt with elevant privs
2) Execute diskpart.exe and perform the following commands:
3) DISKPART> list disk -- find your disk
4) DISKPART> select disk 2 -- mine was 2
5) DISKPART> clean
6) DISKPART> create partition primary
7) DISKPART> select partition 1
8) DISKPART> active
9) DISKPART> format quick fs=fat32
10) DISKPART> assign
11) DISKPART> exist
12) Mount your Windows 10 .iso using your favorite utility - mine is Virtual Clone Drive
13) copy all of the Windows media from the mounted .iso to your newly formatted FAT32 thumb drive. a handy xcopy command for doing this:
xcopy g:* h:\ /s /e -- where g: is your iso mount and h: is your thumb drive
With all this done, you should know be able to hit F12 to enter boot options and have the UEFI find your USB thumb drive.
Some of my research suggested you needed to first disable Secure Boot, enter boot options (F12), pick your USB Thumb Drive, and then re-enable Secure Boot. I didn't have to do that, but several reported having to do so. Your mileage may vary.
Hope this helps someone else... like my boss Scott Prugh who will someday ask me for all this information.