A small how-to for booting external UEFI supports in DELL systems

Reinstalling a new OS on your computer requires prior preparation of an "installation medium", which may be for example a DVD or a USB key, containing an "image" of the new system to be installed. This one has first to be downloaded as an "ISO" file from your system's reference website, before being saved, or burned, to the installation media.
We are then supposed to have a "bootable" external medium ("amorçable" for french speakers), which means that by inserting the DVD or the USB key in their drive, we may "reboot" the computer by asking him to restart from our installation media instead of its hard drive.

It is certainly sometimes necessary to access the "BIOS" program to complete this manip, but most of the time, if it is correctly configured, the computer should always, when restarting, detect the insertion of any external medium and try to read it before moving to its internal hard drive. In other words, it should *automatically* launch the installer provided on the installation media.

.. Except that we found that UEFI removable "bootable" supports may be difficult to be recognized and mounted by the American Megatrends firmware installed on DELL system. Please, don't ask Me why ..

It is not necessary to speak more here about the concept of UEFI, which is the concept of advanced boot loader now replacing the old BIOS. I just want to help everyone with a DELL system and experiencing this irritating problem at installation of a new OS, for example a Linux distribution.


First of all : a (64 bits) UEFI system needs absolutely to find the \EFI\boot\bootx64.efi file on the removable support to recognize it as bootable .

But even like that, DELL systems seem to be not able to mount and use automatically UEFI removable supports. A small complementary parametrization seems to be necessary :

1) Insert your external support (DVD, USB key ..) you want to boot from into your computer ;

2) Restart your system and enter the firmware ([F2] key ..) ;

3) Open the "Boot" index ;

4) The "Boot list Option" should be [UEFI]. If not (i.e. "[Legacy]"), your system is not running UEFI and this proc doesn't not concern you .. Exit ..

5) In "Secure boot", select [Disabled] (if not already ..) ;

6) In "File Browser Del Boot Option", delete any entry related to the USB or DVD ;

7) In "File Browser Add Option", you should see you USB sticks or DVD burner in the selection list, which means that the firmware has correctly detected and recognized it as an UEFI support :


8) Select your external UEFI support ;

9) Select "EFI" :

10) Select "bootx64.efi" ..

11) .. and give a name to your mounting (ex. "USB UEFI"..) ;

12) Your external support appears now in the Boot Options list. Give it the priority #1 in the booting sequence :


13) That's all folks ! Save your changes and restart your system without removing your external bootable support in place.