Unplug the monitor video cable from the video card and plug it directly to the main board video. If it comes on then its your video card. If it still acts the same way then it could be a couple of things (monitor being my first call).
ahhh Make sure that your monitor is actually coming on then. Im sure you know that when your pc is off then (for me) the monitor's power light is orange. Then when I power it up it goes green. See if your monitor's light goes green when you power it on. This will at least tell me if it's your monitor or not.