I'm having an issue with a new video card I purchased. I bought the ATI GFX Radeon HD 6770, and installed it with a 500W power supply (it recommends 450W minimum.) On certain games after a period of play (the period seems random) the screen will go black for a few seconds then return to the game. It doesn't happen with all my games, only two that I've noticed so far: The Witcher 2, and now Skyrim. For Skyrim it took a very long time before it happened but on the Witcher 2 it happened within a couple minutes of play.
This did not happen with my older card.
What is the cause of this and is there a solution?