Nowadays BIOS boot is considered to be “legacy” way of booting and EFI is the emergent default mode. However people still confuse the two and lots of tools for creating bootable media ignore EFI and go with standard BIOS boot.
So, what do you need to boot in (U)EFI mode?
- Obtain OS image/zip that is EFI-aware, having directory /boot/efi on the OS distribution is a good indication of EFI support
- Format USB stick with GUID(GPT) partition table and create a single FAT32 partition named using only CAPITAL letters
- Extract zip or image file into the root folder of your newly formatted USB stick
- Place your USB in non USB 3.0 slot, don’t know for sure why but you cannot boot from USB 3.0 slot
On OSX you can use Disk Utility for the above operations and on Linux, GParted comes to the rescue. I am sure you can easily do that on Windows too, either using standard admin tools or something like Partition Magic, however I did not check therefore can’t advise anything specific.
As for booting Windows and Linux in EFI there are guides how to do that, just search. Although the main requirement is GUID Partition Table, the best way of achieving that on your startup disk is to allow the Operating System to partition the drive during the installation as opposed to manual partitioning.
If you need to dual-boot into say Windows and Linux and you installed Linux in MBR mode but Windows in EFI then Grub will be unable to find Windows installation and you will have to select the correct boot drive on each boot, which will drive you mad eventually. Do not despair though, there is a great utility called Boot Repair, just load USB stick with some Live Ubuntu and then apt-get the boot-repair from there and you will have your situation resolved semi-automatically in the matter of minutes. Writing from personal experience as I was in exactly the above mentioned situation with dual-boot, this utility helped me to convert Linux loader into EFI and now it also allows me to select booting into Windows right from the boot menu.