So my friend has just got his new pc, with a GTX 660, and on every game he goes on, the horizontal lines appear with vsync on or off. Any ideas? Any more details please ask!
Thanks
i had the problem a while ago too; i sixed it by taking care of the drivers. If that's not it then it could be heat.
What heat was yours when it did it?
it was around 80-90 until i messed with gpu settings and under clocked a bit, then added new drivers. I would suggest messing with your gpu settings in the window amd/nvidia