Video Memory

A video card's memory has a big impact on its performance. First, it is necessary to make sure there is enough memory for what you want to do. Here are some basic guidelines.

• For professional graphics, look for a card with anywhere from 32MB to 128MB RAM (or higher), depending on your needs.
• For 2D images, the amount of graphics RAM isn't as important as a high-speed RAMDAC to handle high refresh rates with high resolutions. But, it's probably best to get at least 16 MBs since cards with less usually have older chipsets.
• For 3D graphics, on the other hand, the more RAM the graphics card has, the better. You won't want to go lower than 32MB.

It is also important to make sure the memory on your card has a high enough bandwidth. The memory's bandwidth is the rate at which data can flow through it, and is measured in MB/sec. Basically, as graphic performance increases, so does the amount of video memory and bandwidth you need.

Before an image shows up on your screen, all the data that goes into creating it must first pass through the video memory. The more color, texture, and effects there are making the image look realistic, and the higher the resolution, the more data there is that must pass through the video memory. A larger bandwidth allows more data to pass through the video memory per second. Memory Bandwidth = speed of the memory * width.

Over the years there have been numerous types of memory used on video cards. Today, however, nearly all PC video cards have either SDRAM or SGRAM memory. The width of the memory will be either 32, 64, 128, 256 bits, or even higher. It's not uncommon to find the memory's bit width listed in the video card's title.

In addition, you may notice that many high-end 3D cards have DDR (Double Data Rate) SDRAM or SGRAM. If a video card has DDR it means the card transfers data on both the rising and falling edge of the clock cycle, and therefore has double memory bandwidth. Also, Direct Rambus DRAM (RDRAM), a new all-purpose memory developed by Rambus Inc., may also start showing up on graphics cards.