If you have a "Video Card" make sure that you are hooking that monitor up to that and not the onboard. Also see if the monitor passes its self test. To run the self test just unhook the video cable and then it will say "No signal" after that you will get a colored box that bounces around. If not the monitor is bad and you will need to get it replaced. If you have a "Dell" monitor. The monitor only has a 3yr warranty of its own. If the monitor was ordered with that system then the system's warranty will cover it. When you call in to Dell please have the PPID # of the monitor ready.