I resolved it this way:
- let boot mode UEFI enabled, secure boot enabled
- in BIOS added the USB boot file of the distribution I want to install as trusted for executing:
My BIOS is Phoenix SecureCore Tiano Setup
Boot I flag
Boot Mode UEFI
- Secure Boot ENABLE
Select an UEFI file as trusted for executing
Available File System I select
- Give it the name whateveryouwant then, using tab, select YES.
- so I go to the Boot option, then put whateveryouwant as first in the Boot priority order
- then I was able to start Ubuntu installation in UEFI mode! :)
Before I did all this, I freed the space for my partitions under Windows 8. I read so many guide about UEFI and UEFI install (I give advice to do it!), and tried in several ways. That was the only way I was able to do what I wanted.