General purpose applications, gaming, High Definition (HD) content, and professional 3D modelling all pose unique requirements for the graphics subsystem. The least intense of these - general purpose tasks such as word processing and Web browsing - are easily handled by the integrated graphics of low-cost chipsets.

PCI Express has firmly established itself as the only modern desktop graphics card interface, leaving behind old standards like AGP. Most cards employ an x16 slot connector, though a few x1 cards are available; these are meant to be used as secondary devices for multi-monitor support.

Game graphics are constantly improving, and the easiest way to track the winners in any price range is to keep an eye on our Interactive VGA Charts. For additional details on specific models, be sure to read the Tom's Hardware Guide Graphics Reviews.

HD content may or may not be viewable using integrated graphics, depending on bitrate, compression technology used, and High Definition Content Protection (HDCP) requirements. Both AMD and nVidia insist on the need for discrete graphics cards to allow smooth playback of the highest-quality content, and offer products with integrated HDCP support.

HDCP ensures that HD content cannot be transmitted to a recording device, by requiring a detection device on both the transmitter (graphics card) and receiver (HD display). Both components must contain an HDCP key to ensure authenticity, which is supposed to prevent the unscrupulous manufacture of recording devices with falsified HDCP signatures. HDCP has been adapted to several DVI devices, but any combination that includes a non-compliant component will be forced to reduce image quality.

In keeping with HDCP development, the HDMI interface supports transmitting digital audio and digital video simultaneously at HDTV resolutions through a single narrow cable. Sapphire was among the first to bring HDMI to the PC, in a half-height ATI Radeon X1600 card designed to fit both standard and low-profile enclosures. While a few similar models have since appeared, higher-performance HDCP cards usually use the older DVI standard more common to PC displays.

Professional 3D modelling is generally considered a task best left to professional graphics cards such as ATI's FireGL and nVidia's Quadro series, mostly because the drivers for these cards are optimized for accuracy and OpenGL performance. But given the extreme price premiums compared to similar or identical hardware, semi-professionals and privateers may instead choose a game-oriented card for the task. The chief difficulty is that higher-model game cards do not always provide increased performance in professional applications. In fact, higher clocked card models sometimes beat the better-equipped versions upon which they were based.

While game cards are not usually tested in specific professional applications, the popular test suite SPECviewperf combines bits of the most popular programs into benchmarking viewsets. Now it's just a matter of entering your choice of cards and applications into your favourite search engine.