The 5500 is a lower end card from Nvidia its processing speed is probably far slower than you would expect. I do not know much about ATI, but I can tell you that I have a few systems and one of my systems is much like yours and I have had the same problems with the 5500. The answer to problem is that the game you may be running needs a better card. As an experiment I changed my 6800 GT out of my number two computer and put in the 5500 to see what would happen if I ran the same game in my number two computer as in my other system which originally had the 5500 in it. In short the same thing ended up happening in both systems with almost identical set ups. The 5500 ended up being the problem and I believe its because of its processing power.