I was not able to boot the installer media (USB) with secure boot enabled in my uefi firmware. With secure boot disabled all is working fine.
I saw that opensuse use shim as secure boot loader, which is signed (also) with the microsft key so to be recognized by uefi bios. I'm sure my uefi bios is working becouse i was able to boot a microsoft genuine usb installation media with secure boot enabled, but with opensuse shim i can't boot in anyway.

The motherboard is an ASRock X99 taichi. Someone else has had any similar experience?

My hypothesis is to be in the case described here https://en.opensuse.org/openSUSE:UEFI in the section "Booting the Machine that supports only one signature with vendor provided Keys"

Thank you all.