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Video Cards

Description: The video card (also sometimes called the graphics card or graphics accelerator) is responsible for generating the output signal that is sent to your monitor. This in turn shows you the results of the work you are doing on the system, allows you to interact with the PC, and generally makes the system "usable". The role and nature of the video card has changed greatly over the last few years. As a result, specifying a video card for a system can be either very confusing or rather simple. I'll try to explain how this situation came about.

Traditionally, PCs produced regular two-dimensional output: text and pictures. Games were also traditionally two-dimensional. As games (and other applications) began to acquire more three-dimensional aspects, systems bogged down due to the tremendous number of calculations required for 3D. It was quickly realized that incorporating special processing hardware directly on the video card would speed up 3D calculations and make such software more viable than trying to let the CPU do everything. Today's video cards are almost like miniature "PCs within the PC", complete with their own processor and memory.

Advances in 3D software and hardware now come out at a furious pace. New hardware is constantly developed, and software is written to take advantage of it (and vice versa). The traditional 2D jobs of the video card have been placed in the background, because compared to the difficulty and performance requirements of 3D work, they are mundane. Thus, the market at the present time is such that most video cards are distinguished based on their 3D performance only--almost all will do a good job with regular 2D (Windows, non-gaming) tasks.

The bottom line for the PC buyer is this: if you care about 3D gaming or other 3D work, you will want to thoroughly research the capabilities of various 3D graphic chipsets available, and be prepared to pay for high performance if you need it. If you don't care about 3D gaming though, the selection of video card is the exact opposite: it becomes almost trivial, because aside from ensuring compatibility and basic performance and quality, it's hard to go too wrong. Even inexpensive cards will do a great job for 2D work, and provide adequate performance for occasional 3D use as well.

I am not going to try to spell out all the various features and attributes of 3D graphic processors, because that is beyond my scope here and because the state of the art literally changes every few weeks at times. If you are really into 3D gaming, you will want to supplement the information here with your own research into 3D chipsets and technologies, and decide based on the current state of the market which card to get.

Similarly, if you are designing a system for a specialty application, such as CAD/CAM or graphical design, you will need to choose your specific card carefully. The maker of the software package you'll be using can be a tremendous help in this regard.

Tip: For additional information on video cards, including more discussion of many of the technical details, criteria and features mentioned below, see the Reference Guide section on video cards.

Role and Subsystems: The video card is a key component in the video subsystem, interacting with the system monitor. I also consider it a part of the system processing core, because for 3D work it does a lot of processing and must interact closely with the CPU, chipset and memory. Of course, this depends on how important video is to your PC use.

Related Components: The monitor, motherboard and CPU are all closely related to the video card. The monitor's relationship is fairly obvious, and the capabilities of the two components must be matched in a specific way (see below). The video card must also be selected to match the appropriate bus slot on the motherboard; in some PCs the video is actually on the motherboard, making the choice of video and motherboard simultaneous.

Key Compatibility Selection Criteria: The following are the issues that must be taken into account when considering different types of video cards, even before examining performance issues (which many people usually look at first):

• Integrated Or Discrete: You must first decide if you are going to get a discrete video card, or video integrated onto the motherboard. This decision usually comes down to cost and your video needs. If you go with integrated video, this becomes part of the motherboard selection decision. For more on the pros and cons of integrated components, see here.
• Monitor Type And Interfacing: Your video card must produce output compatible with your monitor, and must use compatible interfacing. The standard video-monitor interface is analog signaling and a 15-pin D-shaped connector. This is a fairly common standard and means most monitors will work with most video cards. Some digital-input flat panel monitors, however, require special digital output video cards and won't work with regular video cards.
• System Bus Interface: The video card plugs into a system bus slot intended for it. On most newer systems AGP has become the standard for video cards, but PCI video cards are still fairly common. There are different speeds of AGP cards and slots. There are also older video cards that use the now defunct VLB and ISA system buses.
• One Or Two Cards: Most people purchase video cards that provide both 2D and 3D processing capabilities, to reduce cost and keep things simpler. However, there are also video cards that focus specifically on 3D functionality, and are used in combination with a 2D-only card.

Performance and Capacity Selection Criteria: There are a great number of performance issues that influence video card choice. Again, the need to consider all these options depends on to what extent video performance is important to you: if all you are doing is basic office tasks at a fairly low resolution like 800x600, almost any video card will do what you want. Also see the quality criteria below, as when it comes to video cards, performance and quality are quite related:

• Video Chipset: The heart of the video is its internal processor, which is called the video chipset. (This component is really analogous to the CPU of the system as a whole, not the motherboard's chipset--darn that confusing terminology!) The chipset is the key determinant of the attributes of the video card as a whole, especially its 2D and 3D graphic acceleration capabilities. The other components determine the specific implementation of the particular card you are looking at, but the video chipset determines the "family" that the card falls into and many of its characteristics in terms of performance and software support.
• Supported Resolutions and Color Depths: Video cards support a number of different output resolutions; the most common are 640x480, 800x600, 1024x768, 1280x1024 and 1600x1200. The higher the resolution, the more information that is displayed on the screen--and the more power and memory is required of the video card. Similarly, support for more colors for each pixel requires more speed and memory storage. See the discussion of refresh rates under quality criteria below, as these are closely related.
• Processing Speed: Some video cards are available in multiple versions, using the same chipset but varying in terms of the speed that the video chip runs. Faster chips produce better performance for 3D applications.
• Video Memory Size: Video cards have their own high-speed memories that are used for two purposes. The first is to hold the color and brightness information for each pixel (dot) on the screen: larger resolutions and higher color depths require more memory to store the additional information. The second is for use by the video processor to speed up and buffer graphical calculations, especially for 3D operation. For the first use 8 MiB of video memory is sufficient for all but the very largest display resolutions. Many video cards now come with 16 MiB, 32 MiB or even more memory; all of the memory above 8 MiB is used for calculations and buffers in software designed to take advantage of it.
• Video Memory Technology: To improve performance, video cards often use faster memory technologies than the regular system memory used by the PC as a whole. Faster technologies such as DDR SDRAM enable higher performance.

Quality Selection Criteria: The quality of a video card can be considered in two ways: the quality of the physical components, and the quality of the output produced as well. (The output quality is closely related to several of the performance issues above):

• Construction: Since the chipset is the core of the video card, it is commonly used by many different manufacturers to make different specific video card types. Better ones of these are better constructed and have better support components than cheap ones.
• Refresh Rates: A conventional monitor display is produced by scanning an electron beam very quickly across the entire surface of the screen. The phosphorescent display then immediately begins to fade and must be refreshed, many times per second. The number of times per second that the screen is redrawn is called its refresh rate (surprise, surprise.) Refresh rates are important because if they are too low, flickering becomes noticeable and this causes eye strain; the usual number considered as a minimum for acceptable quality is 72 Hz. Higher resolutions make it more difficult to keep refresh rates high, as do higher color depths. So to get 72 Hz on a 640x480 resolution output is trivially simple for today's cards; getting 72 Hz on a 1600x1200 output much more difficult because you are dealing with six times as much information. 85 Hz or higher is even better than 72 Hz (though there are diminishing returns; I've never met anyone who could tell the difference between a monitor set to 100 Hz and one set to 85 Hz.)
  High refresh rates require sufficient speed from the video card's video memory and RAMDAC, the component that produces the output signal from the video memory. It also requires that the monitor be able to support the refresh rate being used by the video card for the given resolution. See the discussion of monitors for more.

Warning: When a video card's documentation claims that the card supports a particular resolution, always find out at what color depth and refresh rate it is supported. The highest resolution supported by many lower-end video cards is only at a low refresh rate such as 60 Hz or 65 Hz, which many people find very hard on the eyes.

• Video Driver Quality And Support: Video card performance and stability is as much a function of the operating system drivers that interface with the hardware as it is a function of the hardware itself. Some companies have a much better reputation than others for writing high-quality, bug-free drivers, and also for keeping them updated. Bad or out-of-date drivers can cause a host of system problems, and poor manufacturer support may make it impossible for you to upgrade your operating system in the future.
• BIOS Upgradeability: The video card has its own video BIOS, and like the system BIOS on the motherboard this can be updated to improve performance or correct problems. The comments above about video drivers also apply here.

Important Features: Most of the selection effort with video cards is focused around performance and quality matters. There are also some advanced features that certain users find add value to the video subsystem:

• Memory Upgradeability: Some video cards, especially in years past, allowed you to add more video memory to them if you want to improve performance or capabilities. This is becoming less common as memory gets cheaper and more cards come with lots of it already on board.
• TV Tuners: Some video cards include TV tuners, which with proper software will let you watch TV on your computer.
• Video Capture: High-end video cards sometimes include technology to let you capture and edit video on your system (desktop video).

Note that TV and video capture capabilities can be added to most systems later on, you don't have to buy them as part of the video card.

"Magic Numbers" To Watch For: Most video cards today are sold on the basis of the video chipset, not any magic number. However, the chipsets themselves are sometimes sold on the basis of their "bitness": for example, a "128-bit video card". This usually refers to some internal characteristic of the video card; it's best to ignore such claims and focus on the chipset's overall performance and features, and other performance and quality characteristics.

Performance Impact: Varies from none to tremendous, depending entirely on what you are doing. For routine Windows use, doing lots of 2D number crunching, compiling and other non-graphical tasks, the video card has no impact on the overall performance of the system. For 3D gaming and graphical development, as explained earlier, video performance is essential, and the differences between good and poor video cards are probably more important than the differences between CPUs.

Retail, OEM and Gray Market Issues: Video cards are usually sold as both retail and OEM items. OEM video cards may be very similar to comparable retail cards but may have less memory, slower memory, a slower RAMDAC (reducing refresh rates) or older BIOS (which may or may not be upgradeable by the user). Retail video cards cost more but may be slightly faster. They also often come with some prepackaged software (often games). There are also warranty issues with OEM cards, as there are with all OEM components--you are stuck with whatever the vendor gives you.

With video cards, more than most other components, be sure to ask if the card is OEM or retail, and what differences there are, if any, between the two.

Importance of Manufacturer: This depends on your needs as well. For routine uses a cheap generic card may be fine. However, a critical quality issue with video cards relates to driver support, and that may be lacking with generic cards. The saving grace is that since most video cards today are based on common chipsets, you may be able to get driver updates from the chipset maker if you have a generic. It's still better, of course, to buy a brand name. Most of the better-known big video card makers produce high-quality products.

Typical Component Lifetime: Video cards don't wear out, but they are rapidly replaced by new products. There being something new on the market doesn't make what you currently have obsolete, but over time new software comes on the market that may require extra functionality or performance to run well. As you might expect, the leading edge in this regard is typically gaming.

Unless you really need to continually be near the top of the heap in terms of 3D performance, you won't need to upgrade your video card too often. The biggest longevity issue with video cards once again comes down to driver support, especially when new operating systems come out. If you have an obscure card and the manufacturer won't put out compatible drivers for that new operating system that comes out in two or three years, you may have to get a new card (for rather unfortunate reasons).

Warranty Issues: Video cards are solid state devices and don't generally fail beyond about thirty days. For peace of mind, a longer warranty is still a good idea (and there are sufficient other reasons to get retail boxed video cards that I would recommend that even if warranty concerns aren't that high with these components.)

Driver Support Issues: As I have mentioned throughout this section, video cards have more driver issues than any other component. Driver quality significantly affects performance and stability, not just of the video card but of the entire system. Stay away from video card and/or chipset manufacturers that have a poor track record when it comes to driver quality, or providing driver updates.

Special Specification Considerations: If you aren't sure what video chipset to select, try to stick to a well-known and popular type that is reasonably current. Remember that "obsolescence is in the eye of the beholder". Whatever is the best video card today will be second-best within a couple of months, so don't let that overly concern you.

Next: Monitors

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