Could be the video card, could be the cable attached to the video card, or could be the LCD itself. A simple way to rule out the video card is to attach an HDTV via the HDMI connector. If it works fine on the TV, then it's probably not the card. If you are connecting your monitor via the DVI ports, then try the other DVI port. Also, make sure it is not the DVI cable that is faulty. To rule out your monitor, you can try it on another computer.