HP z840 cannot disable UEFI and go to Legacy

[Hemingstein]

Went into BIOS - disable UEFI is greyed out - clearly i am missing something - how do i disable UEFI?

[old_geekster]

@Hemingstein, welcome to the forum.

Here is the Technical White Paper for the workstation.  On Page 26 it describes the "New UEFI BIOS and features/ legacy support".  If I read it correctly, you will have to disable Secure Boot to use the Legacy BIOS.  Here is what it says:

"Compatibility

The M60 BIOS implements UEFI 2.4, Platform Initialization (PI) 1.3, ACPI 5.0, and SMBIOS 3.0.
The M60 BIOS is capable of running both UEFI and legacy operating systems (what the UEFI Forum calls “class 2 firmware”), without reconfiguration to switch from one to the other. However, when Secure Boot is enabled, only UEFI operating systems that comply with Secure Boot can be launched."

Also, here is the Maintenance and Service Guide for the computer.  It will give you any other information that you need to know about the workstation.

Please click the Thumbs up + button if I have helped you and click Accept as Solution if your problem is solved.

[Hemingstein]

old_geekster - thanks for taking interest. for a while there, i was wondering if i had leprosy.

All the general HP guidance says: "unselect secure boot". And, that seems easy with some systems.

So, if i understand this correctly, For the HP z840, once UEFI is selected/set-up, there is no going back (unselecting secure boot) with that HD, a blank HD must be installed, then unselecting secure boot is an option in the bios.

Please advise.