What do you mean flash?
Are you talking about artifacts? Like small dots on the screen that aren't suppose to be there?
If so it could that your GPU isn't getting adequate power. What is the amp of the 12v line of your PSU? Are you OC'ing? Or it could be that the memory on your GPU is bad so your only remedy is to RMA it. It could also be because of the map. For example, if it only happens to one or two games and if those games aren't stressing your GPU (ie. max settings) then it could be the textures in the game that are corrupted.
It would help if you included more info and perhaps a screenshot of the problem.
