I have a fairly new computer approx. 1.25 years old that has recently stopped working. While playing an online game, the visualizations became striped with red pixels then the pc froze. After a manual restart, the screen is permanently striped with intermittent off color pixels, and the computer shuts down/restarts usually once it reaches the windows logo screen.

The general specs are:
AMD 939 socket processor (i cant get more details due to not being able to find packaging, cant get into pc, and not really comfortable removing heatsync)
WinFast mobo
GeForce 6600GT PCI Express
450W Antec Power Supply
80GB WD C Drive
2 40GB and 1 250GB storage drives
1GB RAM
Superflower metal case with 5 fans. Constant low temps

The pc has these errors no matter which mode I start in, and the visual errors exist before windows even starts, which makes me assume it is hardware. I have tried replacing the power with a 480W Antec, and no changes occurred. I also replaced the internal fans with more efficient models and no change.
I honestly have no clue as to what to attempt, since the issue came on quite suddenly. All suggestions are appreciated.