A graphics card, also known as a graphics adapter, video card or graphics accelerator, handles the processing of images for your computer. Of all the components inside a computer, the graphics card is one of the most likely to fail. Graphics cards have to work very hard, particularly if you play a lot of high-end computer games. When they begin to fail, they can cause a range of symptoms that are sometimes difficult to figure out.
Animation Slowing Down
As a graphics card begins to falter, animation can begin to slow down. Videos and especially games may hang (stop responding); sometimes there will be an error message reporting a driver problem, although no new driver software has been installed. This happens because the card can no longer process graphics fast enough to keep up with the demands made on it.
Incorrect Pixels
The image on your computer screen is made up of tiny dots called pixels. If some of the pixels are the wrong color, it can indicate a problem with the graphics card. Pixels in the wrong color are a type of graphics artifact. If the number of odd-colored pixels increases over time, this may indicate that the card is getting worse.
Wavy Lines
Wavy lines appearing on the screen can happen because the graphics card can no longer render images correctly. Like other artifacts, anomalous lines may not appear straight away but may emerge once the computer has been switched on for a certain amount of time or only when an especially graphics-intensive game is being played.
Fuzzy Picture
Detailed images require more processing power than less detailed ones. The more detail a graphics card has to render, the harder it has to work. When a graphics card begins to fail, it may not be able to produce the required level of detail and the image on the screen will become fuzzy.
Black Screen
When a graphics card fails completely, there is no longer a video signal for the monitor to process. This can result in a completely blank screen, sometimes with a message stating "No Signal."
Other Artifacts
The nature of graphics artifacts will often depend on the graphics that the card is trying to produce. For example, in a three-dimensional computer game where objects are created by drawing a detailed surface over a "skeleton," the surfaces may disappear and reveal the blocky structure underneath.
Graphics Card or Monitor?
It's often hard to tell if the graphics card is causing display problems or the monitor. A failing monitor can cause very similar symptoms to a failing graphics card. You can test the monitor by plugging it into another computer with a working card or by replacing the suspect graphics card with a card known to be functional. If the display problem persists, the monitor is faulty rather than the card. If the problem disappears, this is a good indication that your graphics card is at fault.