In the BIOS menu, set the generation of the PCIe slot to match the generation of your graphics board (Examples: Gen 2, or Gen 3).

Please keep in mind that a display image is sent to only one output connection on your new Quadro or NVS graphics board during boot, so if you only have one monitor connected, and you are not getting a display, it is advisable to power down the monitor, and then switch it to the next output connection on your Quadro or NVS graphics board, and then power up the monitor again. If you are still not getting a display, repeat the steps until you have tried each output connection on the Quadro or NVS graphics board.

It may also help to use a different adapter and/or cable to connect a different make and model monitor to your graphics card, to eliminate the chance that the issue is due to a problem with the monitor, cable, or adapter.