Secure Boot on HP z840

[ha_mann]

Hey,

I've changed the settings from legacy support disabled to secure boot enabled and I just get a Black screen after reboot.

No boot menu, and no chance to get into bios (Removing batterie does also not help). 

To be honest, this is the second time this has happened to me.

I bought a new mainboard due to this error and I did not change any other settings.

 

[Paul_Tikkanen]

Hi:

Disable secure boot.

Then you have to reinstall W10 in EFI mode by booting the installation media from one of the EFI devices (EFI DVD, or EFI USB).

After W10 installs in EFI mode, you can enable secure boot.

[DGroves]

also, make sure your video card is UEFI enabled, cards made in the last 5 years are all uefi capable as i recall

[ha_mann]

Hello
I can't do anything because I see only a black screen 😞

Two Nvidia cards were tested with the same result  > K5200 & M5000.

I think, I have the same problem like Airborne9521.
HP Z840 UEFI video BIOS nVidia K5200 - HP Support Community - 8107949

[Calaudude]

I had similar problem with my HP Z620 box  which I couldnt solve
I used my spare  HPZ620 then

its real strange to brick your pc that way but it happens in HP Z series

[Calaudude]

you can change legacy to secure boot on the fly with mbr2gpt /convert /allowfullos

no need to reinstall

[Paul_Tikkanen]

I tried that  mbr2gpt /convert /allowfullos command on a HP 8200 Elite CMT, running W10 21H1.

It didn't work for me, but I the OP has nothing to lose by trying it.

[Calaudude]

How to convert MBR to GPT drive to switch BIOS to UEFI on Windows 10 | Windows Central

what error you get?

[ha_mann]

I borrowed a NV gtx 1060 and I can start normally with secure boot, but not with Original Nvidia Quadro's o.O