Hello, besides reset BIOS, replace the CMOS coin cell battery with a new CR2032 instead of putting the old one back.

You can not use non-active port for display due to the lack of integrate video in Xeon CPU.  Just make sure that you are connecting the monitor to the Quadro M2000.

@Chino de Oro​ I have tried this:

1. Removed the CMOS battery.
2. Press the power button for 10 secs.
3. Take the blue jumper from PSWD to CMCLR (like you mention here).
4. Wait for 5 secs.
5. Put back the jumper.
6. Insert a new CMOS battery.
7. Plug power cord & turn on.

Computer restarts several times then ... no DELL logo.

(Tried several monitors & cables).

My mistake was to disable "Enable Legacy Operation ROMs".

Would it work if I inserted another type of video card?

Those taken steps were to clear CMOS and reset BIOS to default settings.  Computer was restarted several times, an indication that the BIOS firmware was reset.

If you already tested with different monitors and cables, then yes, you can test with another video card.

While the monitor was without Dell logo, did it show the message of no signals?  What LED color was on the computer power button?  

Post was edited to clean up for clearer information.

Hello,

there are 2 kinds of cpu that fit on that motherboard ( and is valid for xeons too ) : one with onboard graphic , and one without.

Remove the Quadro card, and check if there's an onboard gpu ( in that case you are lucky ).

If you are unlucky, do you have any newer gpu to install to reach the bios screenshot ? By disabling the Legacy Roms , if by any chance that quadro had a firmware variant with only legacy support....

@mazzinia_​

Remove the Quadro card, and check if there's an onboard gpu ( in that case you are lucky ).

Had no luck. My CPU provides no video.

If you are unlucky, do you have any newer gpu to install to reach the bios screenshot ? By disabling the Legacy Roms , if by any chance that quadro had a firmware variant with only legacy support....

I have an NVidia Quadro P1000 which hopefully does not require those Legacy ROMs.

I just picked up a used 3620 tower from a surplus reseller. It was stripped, but still had the CPU. I put in the disks, RAM, and other parts to get it ready to boot. Since I'll be using this as a headless Linux server, I didn't purchase a video card. I typically use the motherboard video just to get the server configured, then remove the monitor/keyboard/mouse. When I went to attach a monitor to check the BIOS settings (VGA or HDMI) I was a bit stunned to not see any video port at all. There is a sticker on the back that says "Non-Active Ports". I got bold and peeled off the sticker and there were 2 HDMI ports and 2 DisplayPorts under the sticker. However, none of them seemed active when I powered on the tower, just a blank screen. I tried all 4 ports. And my Ubuntu OS was not booting, as the disks weren't having activity. I borrowed a video card from another computer, slid it in to the slot (did not load special video drivers on my Linux OS since it wouldn't boot), hit the power button, and started smacking the F2 key and I did get a Dell logo on the screen which after a minute showed me the BIOS screen. Woohoo! I attached a USB keyboard and mouse, and was able to navigate the BIOS settings. My disks were not in the boot device sequence, so I switched from UEFI to Legacy boot and then they appeared. I got the boot devices put in the correct order (because I have multiple disks), and then saved and rebooted. And now I'm getting the Dell logo on each boot, and I'm seeing the systemd output as Ubuntu boots. So now I'm in a happy place. I returned the video card back to the other computer I borrowed it from. Headless mode is working, I can ssh in.

I've never seen a PC without motherboard video, but apparently this is one. In case I can't ssh in and need to attach a monitor+keyboard+mouse temporarily, I'm going to buy a cheap video card so that it is available in case I need it. TIL.

Does your 3620 have a Xeon CPU?  Many Xeon's don't have onboard graphics.  To have onboard graphics, the CPU would have to be changed to an i3, i5, or i7, 6th or 7th gen.

If I remember correctly, the 3620 also takes Xeon E3 processors.  Put the processor model on Intel website to see its specifications.

@Christine Vacher​ You have just saved my day... :)

Thank you both for the information that Legacy ROMs are not enabled after the BIOS reset and mainly for the instructions to turn it on blind ;)

Later I have replaced the current card with nVidia Quadro NVS 315, so I could disable the Legacy ROMs again and enable Secure Boot.