GeForce 660 Ti Artifacts

Hi Everyone,
In October, I purchased and built a computer with the following specifications:
Intel Core i5 3570k Processor
8 GB RAM
1 TB 7200RPM HDD
EVGA NVidia GeForce 660 Ti

I recently put Windows 8 onto the machine, and everything has been working fine for about a month.
Today I started playing Left 4 Dead 2, and suddenly, the game crashed, covering the entire screen in artifacts and I eventually need to cut power off to the system.
Later on, I reboot the system, finding no problem in POST, or even on the Windows 8 boot screen. But as soon as the "lock screen" shows up, the display resolution reverts to 1024x768, and the screen gets covered in green and pink dots, plus, lots of artifacts. I "refreshed" the system, as Windows 8 calls it, about 3 times so far, tried going through the infamous startup repair once, and have installed the GeForce 600 series divers for windows 8 about 4 times so far, all to no avail. Has someone else had the same problem? Or at least knows how to fix it? I would like the answer as soon as possible, with the holiday break coming up and all.