Whether you´re an avid gamer and want to immerse yourself in 3D gaming, or simply want to enjoy watching films on your PC, upgrading your graphics card (also known as a GPU - graphics processing unit) can really make a difference to the experience.
Investing in a good graphics card will result in sharper images, more realistic colours and higher resolutions. It will also dramatically increase the speed with which your PC performs data-heavy tasks such as 2D / 3D graphics or video playback.
PC graphics take up extra processing power, which results in slower PC performance. A graphics card's main purpose is to process and speed up 2D and 3D graphical functions. By taking over many display-related tasks from the central processing unit (CPU), the graphics card allows the CPU to focus on other tasks.
Graphics tasks are assigned to the card's graphics chip. This is where the graphics card processes data, with the help of its drivers. The tasks that the card cannot handle are given to the CPU to process.
The graphics chip stores the processed data (i.e. the information to be displayed on the screen) in the frame buffer.
All the information stored in the frame buffer is finally transferred to the RAMDAC where the digital information is converted to picture signals that the monitor can understand.
Analogue picture data is sent to the monitor through the VGA connector, if present, with digital picture data going through any available DVI connector. The monitor lights up pixels on the screen to create the illusion of a smooth, continuous image.
Graphics cards range from budget cards to high end gaming cards, which can cost several hundred pounds. Obviously the more serious gamer will need to budget more for the ultimate 3D gaming experience, but it isn´t necessary to spend hundreds to improve your computer graphics. A £40 graphics card will still enhance 2D action as well as all but the most advanced 3D games, just to a lesser degree. It's also possible that your motherboard may have an embedded graphics chipset, so you may not necessarily need a new graphics card.
Depending on the motherboard, you'll need a PCI-Express (aka PCI-E) card or, for older boards, a AGP (Accelerated Graphics Port) card. It's best to choose one with PCI Express as this is the interface standard, offering up to double the bandwidth of AGP.
64MB is fine if you are going to use your graphics card for general office tasks, but if you are going to use it for more complex graphics such as gaming, 128MB is the minimum you would require to enjoy the benefits. Of course, the more memory it has, the better the performance.
There are usually three clock speeds quoted: the core clock speed, the memory clock speed and the RAMDAC clock speed. Core clock refers to the internal speed of the actual graphics processor.
Memory speed refers to the speed of data transfer between the card's onboard memory and the graphics processor.
RAMDAC speed refers to the capabilities of the digital-to-analogue converter that provides the graphics output from the card. It doesn't affect graphics card's performance but governs the range of refresh rates the card can support at a particular resolution.
Look for support for both analogue (VGA), and digital (DVI) displays, and S-video, composite video outputs for use with TVs. Some graphics cards also offer a built-in TV tuner and video capture options.