Black screen after new video card

[MDONEZ]

Monitor goes into power save mode after installing new video card

 

[Vlad Rose]

Make sure the video card is seated properly.
Check to make sure your video card has it's power connectors connected properly.
Check to make sure your power supply is large enough to handle the power draw.
If it's an older (non-UEFI) bios, make sure that the primary display isn't on-board.