I had the same issue with a Dell Precision Tower 7810 but I was finally able to install and run Ubuntu 16.04 on the workstation.
Change the following things on BIOS setup:
Disable safe boot.
Change SATA operation to AHCI.
Creating the bootable device (Pendrive):
Download Rufus and Ubuntu 16.04 LTS iso in a Windows machine.
Open "Rufus and select GTP partition scheme for UEFI computer". This will need a functional internet connection as the program will download two files from the internet.
Now boot from the bootable drive and install Ubuntu on the machine.
You can check once after installing the OS if the system is booting or directly run the "Boot Repair" program in live mode after the installation.
After the process is complete reboot the machine, it will detect the Ubuntu installation now.
You can try this process with 14.04 version also.
when the boot list option -UEFI is selected the error is " No bootable devices, strike f1 to retry boot, f2 for setup utility, press f5 to run onboard diagnostics
– Mar 04 '15 at 14:21