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FAQ

Understanding Video Accelerator Cards

The questions and answers below cover a wide range of frequently ask questions about graphics accelerators and related issues.

About this FAQ

Questions

• What is a graphics accelerator?
• What is the difference between a graphics accelerator and video capture card?
• What are the most important features to look for when buying a graphics accelerator?
• What do VRAM, DRAM, WRAM, EDO and all those other acronyms mean?
• What is the best kind of video memory?
• How much memory do I need?
• What is a "video chip"?
• Why do some manufacturers claim to have the same video chip?
• What is PCI?
• What is AGP?
• Which is better, PCI or AGP?
• Some people seem to be recommending not getting an AGP card "yet", what is the deal with that?
• What is a "refresh rate"?
• Do I need a new monitor if I get a new graphic accelerator?
• Does all the hype around 3D really do anything for me?
• How can I decide whether or not 3D is important for me?
• What happened to 2D accelerator cards?
• What is OpenGL?
• What do I need to know to decide between a graphics accelerator with great 3D performance and a low cost OpenGL 3D accelerator card?
• If I am planning to do video editing on my PC, what should I be looking for in a video accelerator?
• Should I be afraid to install a new graphics accelerator card in my own machine?
• What do the "experts" know about installation that might help a beginner get things right the first time?
• What is the best, fastest, coolest graphics accelerator card?

What is a graphics accelerator?

A graphics accelerator is a display board that speeds up graphics programs and adds enhanced, advanced graphics capabilities (such as video playback) to your computer system.  They are also commonly referred to as video cards, graphic cards and VGA adapters.  Simply put, the card makes the graphics and text appear on screen quickly (and accurately).  Some systems come with a "graphics accelerator" built-in, in which case there is no "card" inside you system, but a chipset mounted directly on your motherboard.

What is the difference between a graphics accelerator and video capture card?

A graphics accelerator displays graphics and text coming from the computer while a video capture card brings video from an external source into the computer (records) and sometimes outputs it as well (playback).

What are the most important features to look for when buying a graphics accelerator?

The most important features to look for in a graphics accelerator are the processor used, type of slot it goes in, how much memory it has (and can it be increased), operating systems that are supported and special features such as video conferencing or TV tuner.  Memory is almost always the single most important element for top-notch performance.  Just as adding RAM to you system (motherboard) is one of the best ways to increase system performance, more video memory on your graphics accelerator is generally better.  Then, in order of importance, the net two most important features are the video processor chip and the type of memory used on the card.

What do VRAM, DRAM, WRAM, EDO and all those other acronyms mean?

DRAM (Dynamic Random Access Memory) provides entry level performance for graphics cards.  EDO (Extended Data Output) DRAM has improved performance over standard DRAM (up to 40% faster) and is most commonly used as system memory in Pentium computer systems.  VRAM (Video RAM) is high performance memory for high resolutions graphics.  WRAM (Windows RAM) is less expensive than VRAM but provides fast performance for display of 3D applications.  SGRAM (Synchronous Graphics RAM) provides good speed for graphics display without the high cost of VRAM.   SDRAM (Synchronous Dynamic RAM) runs faster than EDO RAM (because it is synchronized to the system clock) and is commonly used as system memory in Pentium II computer systems.   Nowadays, it is very common to find mid-priced graphics cards using SGRAM, which is cheaper than WRAM and VRAM and much faster than DRAM.

What is the best kind of video memory?

VRAM is the probably best for high resolution graphics while SGRAM or SDRAM is more  suited for 3D acceleration.  Some graphics accelerators come with two kinds of memory in order to balance the tradeoff between performance and cost.

How much memory do I need?

It depends on the applications you are running on your computer and what size monitor you are using.  Most general purpose graphics cards today come with 4MB or 8MB of memory.  Higher performance cards for CAD or animation use can come with 16MB to 40MB (or more) of memory.  There is very little difference in cost between 4MB and 8MB of memory.  For video, 3D and graphics work, an 8MB would easily be the minimum.

What is a "video chip"?

A "video chip" is a chip on the graphics card that provides specialized processing of the display instructions faster than the system's CPU, or main processor, can do by itself.  It is a specialized CPU designed specifically for graphics and video related processing.

Why do some manufacturers claim to have the same video chip?

The company that produces and manufactures the graphics accelerator does not always make the video chip used on the card.  Producing the processor chips that are used in graphics cards is a risky and expensive business.  For this reason, a lot of graphics card manufacturers will use graphics processors made by another company and will just design their own boards (and write their own drivers).  S3 and 3DLabs are a couple of chip makers that are used by a number of different graphics card manufacturers.

What is PCI?

PCI (Peripheral Component Interconnect) is a high speed data bus that is used to connect various peripheral cards with the CPU and main memory.   The PCI bus runs at 33MHz and is used by graphics cards, hard drive controllers, networking cards, sound cards and more.  Until the emergence of AGP, PCI was the standard for high performance peripherals.  PCI will continue to play a leading role in card-based peripherals into the next decade, but many types of high-end, high through-put, demanding peripherals will move up to the AGP interface.

What is AGP?

AGP (Accelerated Graphics Port) is used to connect graphics cards directly to the CPU and main memory.  AGP 2x mode allows the graphics card to communicate with the CPU and main memory at data rates approaching 528MB per second where PCI is limited to 133MB per second.  An AGP card will not work in a PCI slot nor will a PCI card work in an AGP slot.

Which is better, PCI or AGP?

AGP is better because the graphics card has a higher speed data path to the CPU and main memory and because it doesn't have to share that path with any other devices.  The speed offered by AGP allows the graphics card designer to use inexpensive main system memory to store textures instead of having to use expensive local memory on the graphics card.  This means that a correctly designed AGP card can match or outperform the performance of a PCI card that has the same processor but costs more because it has to include more memory.  These and other advantages will become more obvious as AGP become more widely used.

Some people seem to be recommending not getting an AGP card "yet", what is the deal with that?

Early implementations of AGP only supported the 1x mode (has a data rate of 266MB per second) while more recent implementations now support 2x mode.   Some graphics cards that are available now don't yet support the 2x mode and therefore don't take full advantage of the speed that AGP offers.  Just recently a 4x mode was also adopted that allows speeds of over 1GB per second.  In real world usage, AGP 1 did not benchmark at performance levels that were much higher than PCI.  AGP 2 is changing that quickly.  Though early adopters won't suffer, they won't leap ahead of PCI performance as dramatically as people who wait for AGP 2 (or AGP 4x) cards and systems.

What is a "refresh rate"?

The refresh rate is an indication of how frequently the screen display is updated.  Higher refresh rates give a smoother display that allows a more realistic simulation of motion.

Do I need a new monitor if I get a new graphic accelerator?

Not necessarily.  If your monitor supports all of the graphics modes you need then you don't have to get a new monitor.  However, because of changing technology it is unlikely that this will be true and a new monitor will allow you to make the most of your new graphics accelerator with higher resolution and faster refresh rates.

Does all the hype around 3D really do anything for me?

If you do any three dimensional animation or design or even if you play 3D simulations then 3D graphics accelerators can make a difference.  They allow more realistic display of surface textures, clouds, etc. and let you preview your 3D designs quickly without necessarily going through a long rendering process.

How can I decide whether or not 3D is important for me?

If you create 3D designs as a profession or just as a hobby then 3D graphics accelerators can increase your productivity and make you more efficient.   If you just want to play 3D games then 3D graphics accelerators will increase the enjoyment of playing due to heightened realism.  Many of the most advanced (and best) new games require a 3D accelerator.

What happened to 2D accelerator cards?

All graphics accelerators provide 2D functions, even 3D cards.   2D technology has continued to advance, but the improvements are no longer as dramatic as they were in the mid 90s.  3D has all the "buzz" in addition to the dramatic performance improvements, so for the most part, 3D is all you hear about.   In essence, by default, "2D" is implied when you are talking about the type of graphics acceleration found in most cards, even so called 3D graphics accelerators.

What is OpenGL?

OpenGL is the software interface for graphics hardware that allows graphics programmers to produce high-quality color images of 3D objects. OpenGL is a rendering only, vendor neutral API providing 2D and 3D graphics functions, including modeling, transformations, color, lighting, smooth shading, as well as advanced features like texture mapping, NURBS, fog, alpha blending and motion blur. OpenGL works in both immediate and retained (display list) graphics modes. OpenGL is window system and operating system independent. OpenGL has been integrated with Windows NT and with the X Window System under UNIX. Also, OpenGL is network transparent. A defined common extension to the X Window System allows an OpenGL client on one vendor's platform to run across a network to another vendor's OpenGL server.

What does that mean in English?  It means OpenGL provides a standard that allows programmers to write software to display 3D objects that can be easily ported to multiple platforms and operating systems. For instance, a programmer who has written a 3D modeling program to work on a PC running Windows NT 4.0 with OpenGL can take the same basic display routines written using OpenGL and recompile them to run on Silicon Graphics workstations. A good example of this is LightWave 3D. This means that the software doesn’t need to be rewritten from the ground up each time it is made for another platform and that a great deal of time and money can be saved.

What do I need to know to decide between a graphics accelerator with great 3D performance and a low cost OpenGL 3D accelerator card?

You need to know if the card will work with your application, if it has enough memory to store the textures that you will be using while displaying the resolution and color depth that you need, if it will update the screen fast enough for your viewing, if it works with the operating systems and platforms that you will be using, if it can be expanded to grow with you, if you are using 3D applications and not just using your computer for word processing, etc.

If I am planning to do video editing on my PC, what should I be looking for in a video accelerator?

Since a number of video capture boards support overlay for real-time preview it is important to get a graphics card that will support overlay as well.   Also video editing is easier on a larger monitor than a smaller one and larger displays require more memory.  I would suggest you get a display card with 8MB of memory that has good DirectX support.  Compatibility with Windows 95 or 98 and also Windows NT 4.0 may also be important.

Should I be afraid to install a new graphics accelerator card in my own machine?

Not necessarily.  Installing a new graphics accelerator may be as easy as 1-2-3 if you follow the instructions that accompany the new card.

What do the "experts" know about installation that might help a beginner get things right the first time?

When replacing one display card with another it is a good idea to first change the display adapter settings to standard VGA before removing the old card.  This way the display will come up properly with both the old card and the new one.  In addition, setting the monitor type to VESA DDC (if your monitor supports DDC) allows the graphics card and monitor to communicate with each other using the Display Data Channel and thereby avoid settings that the monitor does not support.

What is the best, fastest, coolest graphics accelerator card?

Not a very fair question, eh?  We carry a wide selection of cards that are well suited to a lot of needs.  Without knowing the main purpose of the system the card will be used in makes it impossible to suggest just one card or manufacturer. 

About this FAQ

This FAQ was created and is maintained by DV Wizards' Technical/Sales Support Department.  This is copyrighted material and may not be reproduced in any form without permission.

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