I have a Galaxy GTX 640. I had it for about 2-3 months and was working fine. I played League of Legends on it and some weird artifacts happened. Then when i reinstalled League of Legends. I slept about 4-5 hours long and when i came back to see if league of legends was done and the updates as well i saw pixels aligned in red square blinking everywhere. I need help what the problem is.
Op, the reason artifacts usually start occurring is due to heat. The only other reason they appear - is hardware issues.
Based on what you've said, I reckon your card needs to be RMA'ed. I'd put my money on possible VRAM corruption.
It would have nothing to do with the software - artifacts don't appear due to software issues.