990, adding graphic card

The on-board video is suppose to automatically disable itself.

But it seems these OptiPlexes sometimes need some extra persuasion. 

https://www.dell.com/community/Optiplex-Desktops/9010-hangs-during-boot-with-Radeon-R7-250/td-p/6166866

and

https://www.dell.com/community/Optiplex-Desktops/5040-GPU-upgrade-SFX-PSU-installed/m-p/6186829/highlight/true#M28818

I tried all the steps nothing has worked so i decided to put the card in my main rig to see if it works. I currently have a 1070 in. After i put in the card and plugged everything in i had the same problem as the other system. Does that mean the card is broken? and is it 100% that? 

Also the dell motherboard has a 5 pin connector to plug in the power switch, i moved it to a new tower and this one has 2 pin connectors for power,reset and lds. Is there a converter i can use or do i need to splice the wires together for it to work? Do you know which pin is which maybe? Thank you very much

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@hurricano wrote:

1. I decided to put the card in my main rig to see if it works. I currently have a 1070 in.

2. After i put in the card and plugged everything in i had the same problem as the other system. Does that mean the card is broken?

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1. Good troubleshooting

2. Sounds fairly broken to me.

Onboard is not supported when a card is inserted into the X16 slot.

If you could see something it would have the following on the screen.

Attention: Unsupported Video Configuration Detected

System halted!
Attention: Unsupported Video Configuration Detected

Action is Required

This computer has an add-in graphics card, but the monitor is plugged
into the integrated video connector.
To attach the monitor cable to the add-in graphics card:

1. Shut down the computer
2. Plug the monitor cable into the add-in graphics card connector.
This may require a video adapter or video adapter cable.
(provided with the system)
3. Turn on the computer.

This message should not appear after completing these steps.
For more information or help, please refer to the system documentation.

@Tesla1856​ I realize I’m a few years late, but I’m about to put a video card into a dell optiplex 990 with intel integrated graphics. I’ve checked & my bios has no option to do anything with the on board graphics. What might I do if I run into this same problem? 

BIOS has no option to do anything with the onboard graphics because it's automatic.  Adding a graphics card disables onboard graphics and graphics card must be used for monitor connection.