First you just need to ensure the BIOS is set to UEFI, disable "Legacy option ROMS" and enable secure boot (Secure boot is optional). (Figures 1 - 3)
Figure 1
Figure 2
Figure 3
Follow the steps indicated below to install Ubuntu 14.04/15.04 on your Dell computer and configure the BIOS to use SHIMx64.EFI (Required for normal operation):
Download and create a bootable Ubuntu Linux USB key. (You may want to use a 3rd party application like Rufus to create the bootable USB key.)
Once the UBUNTU install from the USB key is finished and you reboot the system, Press F2 when you see the Dell logo to enter the BIOS. Once in the BIOS choose Boot Sequence.
In the boot sequence screen that pops up click on the Add Boot Option button. The Add Boot Option window will pop up. Type a name in the Boot Option Name text area (Ubuntu for example). Click the button to the left of the File Name text area. The EFI Boot Selection window will pop up. (Figure 4)
Figure 4
In the File System drop down menu choose "FS0:". Then using the Directories section, navigate until you can choose SHIMx64.EFI file in the Files section. (Figures 5 - 7)
Figure 5
Figure 6
Figure 7
Type a name in the Boot Option Name text area (Ubuntu for example). Click OK. Click Apply. (Figure 8)
Figure 8
Exit the BIOS and you should now be able to boot to UBUNTU normally from the boot drive.
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