HP Z640 Workstation "Pre-Video Graphic Card error"

[SparkyTech934]

Hello.  I just bought a used HP Z640, and was in the initial stages of setting the device up at my home.  I started by clearing the CMOS, and reverting any changes by the previous owner of the device in the firmware so I could set things up how I wanted them.  I noticed that legacy support was enabled, and secure boot was disabled, so I changed the BIOS setting and set it to 'disable legacy support, enable secure boot' becuse I was going to install windows 10 (which of course has built in secure boot support).

Changing that BIOS setting is where my problem began.  As of now, the machine will not POST  becuase it doesn't like the vBIOS of the GPU (a GTX 660).  The POST error code is red LED, 6 beeps, and 2 second wait.

Basically, my predicament is that now that the computer won't even get past the POST, I am unable to even enter the BIOS and revert to 'enable legacy support and disable secure boot' to get back to where it was working previously.

I have tried the following:

• Clearing CMOS to revert settings (both with CMOS button, and by taking the battery out for 15 or so minutes).  This did not work, I assume because clearing CMOS does not affect UEFI/Secure boot settings.
• Taking GPU out of the machine, and reseating it.  (obviously was a long shot, but was worth a try).

I am at a loss, and need some help with this.  I'm a software developer and have plenty of hardware experience, but I feel like I kind of am stuck in a corner here, with not being able to even get into the machine's BIOS.  I was thinking that I could try and get my hands on a newer GPU with UEFI support, but even then, there is only a 6-pin PCIe cable in the Z640, and most modern cards require an 8-pin connector.  I'm honestly shocked that a simple firmware setting change could render the device so useless.  Please post any suggestions, I appreciate your time and effort!

Edit: 10/6/2021  1:13PM

I thought of a few workarounds that I will try, however, I would still love suggestions for this issue.

1. Use a second power supply to power a newer, UEFI capable GPU to get back into the BIOS and change the setting back
2. Try and use the failover BootBlock mode to re-flash the BIOS from a USB drive.  This option will most likey be uneffective due to the fact that it only allows a re-flash if it detects corruption which I do not think is the case here.

I will update again if I find a solution.

[itsmyname]

@SparkyTech934 -- is this your computer: HP Z640 Workstation (zworkstations.com)

Do you have any of the GPUs listed on this page?  I hope that the computer will POST when one of those GPUs are connected.

[SparkyTech934 · Accepted solution]

Alright, so I was able to remedy the issue.  I tried a few things, and since there was no video output, I'm not 100% sure exactly what the fix was, but I have a hunch, and will explain in summary.  My order of operations is below:

1. Removed all unneccesary components from the machine (this would be the setup I used for the rest of the troubleshooting).  This included:
   1. Optional CPU board + RAM that was installed on it
   2. Wireless card
2. Took out CMOS battery, waited more than 30 minute
3. Simultaneously to clearing CMOS, removed the GTX 660 (the original card that was being rejected by the BIOS), and replaced it, in the same slot (top slot) with a low profile video card.
4. Replaced the CMOS battery, booted the machine

At this point, the video card error 6 beeps, accompanied by red LED, 2 second pause came back.  No success.  I continued below

1. Moved the jumper on the BBR (Boot Block Recovery) header, shorting the pins towards the rear of the case.
2. On another computer, created a flash drive image with the HP software on the Z640 support site. (extracted files and then followed prompts to make 'recovery drive').  Then plugged the USB drive into the back of the machine
3. cleared CMOS again (CMOS button on board this time)
4. Booted the machine into BBR mode.  8 beeps, accompanied by red LED (normal activity for BBR mode).  The flash drive began pulsing/flashing before staying lit constantly. Eventually (after a few minutes), the machine's fans ramped up to 100% speed.
   1. NOTE:  At this point, with the observed behavior, it did not  appear to be doing what it should in BBR mode.  All documentation regarding this mode say that if successful, the machine would boot twice and then shut down.  I am unsure if BBR + USB recovery fixed anything.
5. I force powered-off machine since it was in error state
6. Replaced the jumper back to original pin location.
7. Started the machine again (now in normal boot mode).  6 beeps, accompanied by red LED, 2 second pause persisted.

With trying  BBR mode without any knowledge of of success/failure, and clearing CMOS still having no effect, I was begining to feel like this was going nowhere.  My last attempt is detailed below:

1. Cleared CMOS again (CMOS button on board)
2. Switched out video card for another low-profile option that I had laying around (this one identified as a Geforce 210 GPU by Gigabyte, revision 6.0)
3. Booted machine.
4. Success!  I saw an HP splash screen, and was able to access the BIOS after one more CMOS reset.

After getting to this point, I did the following, and I would highly recommend others do the same:

1. Upgraded BIOS manually to the latest version (HP Z640 - version 2.57 as of May 2021)
2. Set BIOS to factory defaults after upgrade.
3. Put in the rest of the hardware.
4. Tried another GPU (RTX 2060) and changed the original setting that messed me up
   1. 'disable legacy support, enable secure boot'
5. Everything still worked fine after that.

​Summary

Alright, so to summarize and play some detective work, I believe that the fix was as simple as replacing the video card with another unit that the system was able to interface with in UEFI only mode.  I would like to think that using BBR mode and recovering the BIOS was a help, but it seemed that while using BBR mode, the machine did not exhibit normal behavior.  To further compliment that theory is the fact that my BIOS version hadn't changed after using BBR mode, so I'm doubtful that a BIOS flash happened when trying to use the feature.

I truly hope this post/thread can help someone else who accidentally picks a fight with HP's hideous firmware.  I will update if I forgot to mention anything.