@4Kals 

There is no help because what you are doing is NOT supported. 

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.

Optiplex SizesUn Supported video configuration System Halted.

Try a different GPU.  If the GT 730 was bought used or refurb, it's entirely possible it's defective.