Do I need to create a bootable flash drive that is specific to booting EFI mode or can a normal USB bootable drive function, for older BIOSes and newer UEFI firmware? I can easily boot into the EFI mode, on a DVD drive, but have trouble getting a flash drive to function in the same way. This happens on multiple ultrabooks and newer desktops. This is when I am attempting to install Windows 7 or Windows 8.1.
Booting into UEFI mode from USB drive
Here's two possibilities:
1. Make sure the USB stick is formatted with FAT 32 before creating your Bootable USB for UEFI.
2. If secure boot on your UEFI machine is turned on, more than likely your Bootable USB is not a signed bootable device. So that means you may have to turn off Secure Boot.
Try either option one at a time...then both if one at a time doesn't get you the desired result.
It will also depend on your motherboard, you might be able to use 'legacy boot' and put it on top of boot order.
You can use RUFUS it's a (new?ish) tool that can create usb sticks for uefi. I installed windows10 using that.