I have a similar issue.

The grafic card shows the F1/F2/F5 message only once after battery removal.

Is there any final solution ?

Well, my solution which I used currently..

I removed power cord and mainboard battery - where 5 minutes was not sufficient, following I waited an hour to retry.

I placed an old grafic card (FX1800) at PCI Slot 2, connecting a monitor via DVI.

(where - I expect other cards will also work, however, after successful fixing this issue I do not try this).

Placing battery on the board, mounting the power cord and statring the machine, it takes about 90 seconds

(long time, but maybe because of having 1024 GB LR-ECC-DDR-RAM installed) until the machine shuts down and restarts automatically.

After additional 90 seconds, the further above mentioned F1/F2/F5 message is shown.

Using this oportunity: selecting F2 opens the BIOS setup.

There, in section Video, a selected PCI Slot 2 to be the primary video adapter and saved this ("apply").

After setting this, any grafic card in PCI slot 2 is detected (? no ... used) correctly for the system boot, also

showing all the machine startup information.

My conclusion: yes, there is a bug in the BIOS version A34, where the auto detection of grafic cards

is incorrect, instable or simply not working.

So....thank you Dell in advance for taking care for this issue, even if the machine is EOL.

And, why F12 boot menu gone? Even there are some issues in hardware, I still want to boot from USB disk to see what's happend.

Before getting above screenshot, I've pressed F12 again and again, but the boot menu not shown.

And, there is no hard drive indeed, but I've insert USB disk and the BIOS can identify id successfully.

So, I want to boot from USB disk in which the Windows PE deployed. But I have no change since the boot menu gone, even I've preesed F12 again and again.

You are talking about a 10 years old workstation that is considered end of life.  BIOS version A34 was the last release in November 2020.  Dell stopped supporting this EOL workstation.  

In your case, let replace the coin cell battery with a fresh new CR2032.  Reset CMOS with the jumper.  Adjust time/date and hardware settings, then test again.

The coin cell battery voltage is 3.0V as I measured. Anyway, I'll replace a new one and see what's happened next.

You are talking about a 10 years old workstation that is considered end of life.  BIOS version A34 was the last release in November 2020.  Dell stopped supporting this EOL workstation.  

That's OK. Then I can communicate here with other Dell old users who are not EOL.

The statement about Dell stopped supporting end of life system was in response to your request:

So, please show messages in BIOS as possible as you can. Please and Thanks!

Therefore, support from Community users is all you are going to get.

@Chino de Oro​ Yes. I agree. Thanks!

What I guessed, it's correct. It's the bug of BIOS.

The K1200 card works on T7810. So I moved it to T7910.

But there is no display on T7910. That's the reason I created this thread.

Flollowing post inspired me: Dell bioses have some bugs with GPU autodetect. So I use another card P600 on T7910, the display works!

https://www.dell.com/community/en/conversations/precision-fixed-workstations/dell-7910t-with-nvidia-quadro-k4200-gives-black-screen/647f91b4f4ccf8a8de3486f4

Since it's a bug of BIOS. Any reply in this thread shouldn't be Marked as Accepted Answer before fixing it officially.

Don't worry too much if this thread will be having an accepted answer or not because ten of thousands of the T7910's owners out there are still enjoying their workhorses.  You can hardly find or count how many thread/user are awaiting for a BIOS fix.

It seems that your no display issue was resolved by testing with a different video card, not with a BIOS fix.  But the main query of this thread is asking for an official BIOS fix.  A glitch or a bug was commonly used when a person did not know the exact cause of a problem.  To identify the issue, Dell engineers and programmers must be able to recreate the problem(s).  If the issue was specific to your system only, there is no issue to fix even if Dell want to.

The goal of our community is helping members solving computer problems, especially for those with systems out of warranty.  Only about 1 out of 10 users or less would come back to report the results and closing their threads with accepted solutions.  Accepted solution or not, your thread of requesting BIOS fix may not help any of T7910 owners with system issue.  Hence, I (we) don't expect much out of you either.

@Chino de Oro 

To identify the issue, Dell engineers and programmers must be able to recreate the problem(s).

Re-producing is easy. Just need to flash BIOS A34 and insert K1200 card into T7910.

It seems that your no display issue was resolved by testing with a different video card, not with a BIOS fix. 

It's just a workaround. I still want to use K1200 card on T7910. But no display now.

The root cause is still in BIOS: Why K1200 works on T7810 but T7910?

The goal of our community is helping members solving computer problems, especially for those with systems out of warranty

So, are you an employee of Dell? I saw you posted many many responses in this community.

For K1200 card no display on T7910 issue, it's better if there is explaination from Dell offically. Or better more, releaseing new BIOS version to fix it.

But I know, T7910 is out of support from Dell. 

I'm an engineer. I don't stop at solving. I need to figure out what's going on, the root cause, one the other hand.