Radeon HD 6870 Artifacts Just Started Happening

Ever since I've had this card, it seems like its always been a little weird. Sometimes when I would boot my computer up from being off for a day or two, then I start searching something in google, and the screen would go blank for a second and an error message would pop up saying that "Display Driver stopped responding and has recovered".
So just today, I booted on my pc and noticed these small blue lines all over the screen and various artifacts in games too. I tried rebooting, uninstalling/reinstalling display drivers. I did overclock it to 920MHz from 900MHz and bumped the Memory speed up a bit, but that was almost a month ago. I tested it then using furmark and it showed no signs of artifacts then. So I set everything back to default

My specs:
Intel Core i5-2500k
GSkill Ripjaws 8GB
Windows 7 64bit
Gigabyte Z68P-DS3
Sapphire HD 6870 1GB
Antec 900W PSU


Only today have these artifacts started popping up all over the place.
Is there any way to fix this?
Here are some screenshots:




Thanks for your time.