Wow I can't believe that I didn't think of that. What is the exact make and model? Radeon HD 5450 is for the graphics chip however the card would have been assembled by another manufacturer (see here: Newegg.com - Radeon HD 5450). I ask because as you can see there are different ones and a few that I saw appear to have an additional spot for a power source whereas another didn't. If you don't have everything connected correctly then the card won't get enough power to function properly. See and follow the manufacturer's instruction manual. Also note the minimum recommended wattage for your PSU is 400 whereas your PSU is 250 watts. The card won't function as well with so little wattage than it would if your system met the recommended requirements.