So, I've been trying to install Windows 8.1 x64 on my Mid 2011 iMac and I keep running in to the same problem where after my machine restarts after the Windows partition is made it says "No bootable device...". Basically, I found a way to let Bootcamp make a bootable USB since my iMac no longer supported it. I edited the info.plist so that the option was available to me. Once I went through all the steps of formatting the USB to FAT and making it a Windows install and partitioning, my machine finally restarted to install Windows. After that I got the "No Bootable Device" prompt. I have tried holding the Option key and selecting the USB to boot from but I get the same results. I've also tried installing from different USBs/HDD with no success. Also, only one external drive is connected to my computer at a time. Is there anyway to fix this issue or is it unavoidable because my machine has an OpticalDrive? Currently I can't find any simple fixes for this specific problem aside from buying blank CDs and burning the Windows ISO on to a disk.