What you need to know about RAM in graphics devices

Source: ComputerShopper.com

RAM on a graphics card is memory (often called video memory) that is specifically dedicated to drawing images on your screen. While most graphics cards come standard with a certain amount of RAM, most can be upgraded to include more.

The more video RAM you have, the more quickly images will be drawn. As PC/Computing reviewer Chris O'Malley observes, graphics can be a huge resource drain on your computer's performance:

Whether you want to kick your current system's performance up a notch or optimize a new system, you need a fast graphics card. It's the most effective way to speed overall system performance.

The amount of RAM you need will differ depending on the screen resolution and the number of colors you use.

Joseph Moran explains:

"To use 24-bit [16.8 million] color modes at a resolution of 800 by 600, for instance, you'll need 2MB of RAM. With the same memory, you can handle a color depth of 16 bits [65,536 colors] at a resolution of 1,024 by 768, but you'll need 4MB to step up to 24-bit color at the same resolution."

Jon Hill of Computer Shopper advises:

"Buy as much memory as you can afford, taking 2MB as a minimum and 4MB as a necessity if you plan to run in true-color mode at 1,024x768 resolution. Serious 3-D users may want to consider cards with even more memory, since a 4MB board's support for double-buffered 3-D peaks at 1,024x 768 resolution and 16 bits per pixel."

Several different kinds of RAM can be found on graphics cards and graphics accelerators.

Video RAM, or VRAM, is different from conventional system RAM in that it is dual-ported -- it can both send and receive data simultaneously -- while system RAM can do only one task at a time.

A less expensive alternative to VRAM is Dynamic RAM, or DRAM. Performance will be slower however, because DRAM, like conventional RAM, is not dual-ported. It can only send or receive at any given moment.

Synchronous graphics RAM, or SGRAM, is a very fast type of RAM that operates at the same speed as the graphics card itself. Specially designed to be used on graphics cards, it improves performance on tasks such painting in a large block of color. Because it's so fast, it's expensive and used on many high-performance cards.

Window RAM, or WRAM, is a kind of dual-ported memory that is specifically designed to speed up certain graphics tasks such as bit block transfer, or BitBLT. With built-in support for BitBLT, WRAM can more efficiently move rectangular blocks of bits -- a very common type of graphic in the Windows environment.

In addition, as Joseph Moran of Windows Sources points out:

"WRAM requires fewer transistors for a given amount of memory than VRAM, which results in a lower cost compared with VRAM."

You'll also find EDO DRAM on some cards. Extended Data Out DRAM is slightly slower than SGRAM, and therefore costs less.

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