Has it worked before? What, if anything, has changed prior to the issue (assuming it worked previously)? Also, what make/model is your power supply?
I got the card off a friend. Its when i plug it into the mobo that the monitor dosent work. I made sure i installed it correctly. The monitor works when i unplug the card. Im using a atx 250pa for power. I replaced the old power source (220wat). The new one makes 250 wat. I tried disabling the integrated graphics and reinserting the card yet im still have the blank screen.