After running Skyrim for about 30 mins or so straight, I start to get these occasional small blue squares that quickly flash on the screen, usually in a corner of the screen. I have an HD 7870 OC edition. My GPU isn't overheating, as it typically hovers around 70 degrees C under load. I also ran DxDiag and it says no problems detected. I'm worried this may be a GPU issue anyway though, anyone know what this means?