Does the computer still power on? Just try removing the video card if you have one and clear the bios. and then try rebooting. Normally lines can be called banding sometimes they are orange, red or even other colors. I've noticed a lot of the video cards that come in systems now days have these little tiny fans that spin insanely fast and soon die. If your computer has one of these lower end video cards with the little fan that might be the problem.