My card had been acting up, showing faint white lines across the screen following the mouse, then when I loaded HL1 the visuals were VERY messed up, a few days ago the whole thing went haywire and now when i turn my PC on it says "monitor self test, check cables" so i check the cables, take out my video card and put it back in, unscrew the cables and put them back in, and it still does the same thing. Is my card dead, or is it the motherboard?