Video Card Issues

Hi,

Just over the past day or so my computer has gone from completely operable to the point where I can hardly turn it on. It began with odd artifacting, wavy blue horizontal lines across my screen, followed by my computer freezing. On reset, I noticed the wavy blue lines were still there on the black screen, leading me to believe it has to do with my video card's hardware.
I let it all cool for about an hour, came back, and it appeared to have resolved itself; unfortunately, while trying to download new graphics drivers, the problem repeated itself, and I reset again in safe mode. I managed to download and install the drivers in safe mode, but this didn't solve the problem. Upon further resets, the artifacting and lines remain the same, but the system doesn't even prompt me to start in Safe Mode, it just tries to start normally, Blue Screens, and then resets. I managed to catch a glimpse of the Blue Screen, stating that something is not "fully ACPI compliant," but I assume this isn't actually the problem.
Using the PlayTool site for diagnosing the problem, my issue seems closest to "Video RAM artifacts," but I was just wondering if anyone here might be able to give me some better insight on what my issue is. Thanks!!  

In case anyone needs to know:
Video Card: nVidia GeForce 9800GT
OS: Windows 7 64-bit
Motherboard: nVidia nForce 780i