Acer- Emachine - Gateway to name a few... There is no option to disable it at all-- it is missing.
Microsoft REQUIRES that all x86/x86-64 machines have the option to turn off Secure Boot...
I had a friend bring me his All in one with Windows 8
Acer Aspire AZS600-UR15
and wanted me to install Windows 7 on it- there was no option to turn off the check.
Windows 7 would pretend like it would install then at the point of installing boot loader - Fail- even when I placed a fresh drive int the machine.
It would not let it write to the boot sector.
I looked and there was nothing -- the only options were - to control boot order- check for extra hard drives and turn to compatibility mode.
I had to end up restoring the Windows 8.
Secure Boot was obviously disabled.
It shouldn't even let you boot from a DVD if Secure Boot is enabled.
Compatibility mode? Perhaps they're calling it that? By the way, Secure Boot doesn't prevent the writing of the boot sector, I don't think. I think it only prevents booting from a boot sector that doesn't have a valid certificate stored in the UEFI. I think. So if malware overwrites it, you will be blocked from booting... and will have to run the recovery DVD to re-write the boot sector.