HP Z840 doesn’t start after enabling secure boot

[SvartDraken]

Hi everyone, I have recently restored an HP Z840. The device booted just fine so I formatted the disk and installed Windows 11. Then, since I had previously disabled it to boot from the USB key, I went back to the BIOS and re-enabled Secure Boot. Now the PC doesn’t start anymore.

I have researched this topic and apparently there was an option for “UEFI except video”. However, despite seeing it, I had no idea what it meant. In fact, I thought Secure Boot was purely storage related. Instead, I now learn that the installed GPUs (3 x Quadro K620) run in legacy mode. I don’t own newer GPUs to test. 

I have already tried the obvious (CMOS reset, battery removal, blind BIOS, etc…) but it didn’t work. I also tried to download the BIOS image to flash it from a USB key, although unsuccessfully. In normal configuration, the power button lights up white and I get no error beeps, but I get no video output (monitor turns on, and then back off after a second, no image shown). When I move the jumper to boot block recovery, I get the 8 beeps and red light. However, nothing happens when inserting the USB key with the BIOS file. 

Any recommendations will be greatly appreciated. Thank you in advance. Kind Regards 

[DGroves]

you are not being clear in your post so i'll post some info

secure boot  REQUIRES a UEFI enabled bios (which the z840 has)

secure boot has to be enabled in the bios BEFORE INSTALLING WINDOWS, if you enable it on a drive that was formatted in legacy mode (secure boot disabled( then windows will fail to boot until secure boot is disabled

trying to flash a bios when not really understanding the problem,......... is a great way to cause more problems and possibly brick the motherboard 

hopefully you have not corrupted the bios, but 8 beeps does indicate a corrupted bios

try a crisis bios recovery

https://h30434.www3.hp.com/t5/Business-PCs-Workstations-and-Point-of-Sale-Systems/Bricked-Z840-MB-fr...

once the bios is functional try the directions below

power off remove power cord

press power on button till beeps/pwr light are off

open cover, remove all video cards except for main card that connects to monitor

locate the small silver cmos coin battery and CAREFULLY remove it

(without damaging the battery socket) if unsure on this leave it in

now locate the small yellow button near the cmos battery and press for 10 sec

reinstall cmos batt (if removed) replace side cover connect monitor cable and power cord

now power on, while tapping the "F10" repeatedly to enter the Z840 bios

if the bios is not corrupted and you did not enable the bios "compute" option

then you should get a display and be in the bios set date time TOUCH NO OTHER SETTINGS

and save and reboot

if system works, do not reinstall the other video cards there is no practical benefit in doing so

a HP os restore disk/usb key can be downloaded from the HP "cloud recovery" web page

google HP cloud recovery for the link

last, READ/Google each bios feature to learn what it does before blindly guessing what you think it might do if changed

[SvartDraken]

Hello, thanks for your reply 

I’ll tru to explain the issue a bit better. First of all, when I started the device for the first time, I went to the BIOS to change the secure boot setting to “Secure Boot off, legacy support on”. This is a single setting. This apparently also changed the other setting in a different menu, where you can choose “UEFI”, “UEFI except video” and “legacy”, I did not touch this setting. After installing Windows 11 from the USB key I restarted the device and returned to the previous menu. I have selected “secure boot on, legacy support off” and restarted the device. This is what triggered the issue. 

The system thinks there is no video card and it will not start. It doesn’t allow me to enter the BIOS. I have said in the post that I have done all the tests you have recommended. I have done the CMOS reset, I have removed the battery, I have moved the password reset jumper to “PSW” and “BB”.

The 8 beeps do not indicate a corrupted BIOS. Again, as said in the comment, this happens when I switch the “Boot Block Recovery” jumper to the active position. The beeps are normal and expected behavior, it does not happen when the jumper is in inactive position. However, in this mode, the device still does not provide a video output and, apparently, doesn’t detect the recovery file on the USB key. This is the same BIOS that I have installed on this motherboard two days ago. 

Other than bios recovery, I don’t have other ideas to fix the issue. I don’t have access to a newer GPU with UEFI support.