I back to you because i can't install audio kext....
I tried Applehda patched ALC255 and 256 but not works...
Have you got solution for me ?
Huummm Smeels good !
I plugged the usb key in the internal usb port and the system allowed me to install HS.
After install of clover i putted the EFI folder you shared to me in EFI partition.
Actually i try to install network , audio and nvidia drivers.