My monitor fails to start up when I turn my PC on?

My monitor has recently stopped turning on whenever I start up my PC. I have replaced the cables connecting the monitor to the graphics card, plugged the cable into a different socket on the graphics card and even reseated the graphics card itself and yet the screen still fails to start up. It is not a problem with the monitor as it starts up fine when connected to my laptop. Does anyone have any ideas as to what may be causing this?