Common Video Card Bus Types

The video card normally plugs into the same type of expansion slots that other cards do. Systems built before the mid-1990s used one of the following obsolete bus standards:

• ISA

• VL-Bus (VESA Local-Bus)

• EISA (Enhanced ISA)

Current systems feature one of these video interfaces:

• PCI slot

• AGP slot

• Integrated graphics

Built-in video uses two different types of memory:

• Dedicated memory chips on the motherboard; used primarily with portable systems that use a discrete graphics chip instead of chipset-integrated graphics

• Shared main memory (also known as Unified Memory Architecture [UMA] ); used primarily with systems that use chipset-integrated graphics

There's a double whammy on system performance if your video comes from your motherboard's chipset:

• Built-in video that uses shared main memory normally is slower than video that uses separate memory because main memory and video memory have different characteristics and speeds.

• Sharing main memory means there's less memory for programs. For example, if a system with 256MB of RAM uses 32MB for video, programs only have 224MB of RAM to work with.

What can you do about this?

• If your system shares main memory for video, you normally can adjust how much memory is set aside for video by making adjustments in the system BIOS setup program. As little as 9MB or as much as 64MB of RAM is shared built-in video; the exact amount varies by chipset, operating system, and the amount of main memory installed.

• Install more memory. Many recent systems also increase the amount of memory available for graphics as the total amount of memory increases . Check the system's or chipset's technical documentation for details.