I tend to go with what dav8d said about seating the video card. Sometimes the bracket of the card is off just a fraction so it doesn't allow proper seating. Disconnect the monitor, take the screw out of the mountin bracket. Reseat the card. Hook up the monitor. Now look at the mounting bracket hole alignment. It should be perfectly aligned. If not you will have to loosen the screw that holds the bracket to the board, hold the boad while tightening the mounting bracket so it doesn't move. I just went through that with a newer chassis.

I must remember to remember what it was I had to remember.