I have an XFX Radeon 6950 graphics card overclocked from the factory. I have had problems with it since I got it. The first problem was it would sometimes quit working if you bumped the computer just right this would require flipping the power switch and jiggling the power cables and turning it back on. Now something new is happening. While playing games (Minecraft for example). It works just fine in a small window. When I maximize it the screens go black. When I press Ctrl-Alt-Del they come back on. The default GPU clock is 830 MHz. When I lower it to 700 MHz I no longer have a problem. Its somewhat of a fix but I don't want to lose my performance.