If the CPU (Central Processing Unit) is the brain of a computer the Video Card is its imagination. Really, anything the CPU can think up, the video card can beautifully create it in a 3D image. A Video Card's function is to take information from the CPU and convert it to an image, and then send that image to your monitor. Without video cards, modern gaming would be impossible. While a CPU can render simple 3D images, the video card excels at drawing complex scenes very fast. A modern video card can render a 1080p scene at 60 frames-per-second. That means that it calculates and draws over 2 million individual pixels 60 times every second.
Video cards communicate with your computer through a few possible interfaces. Older Video Cards used the PCI ( Peripheral Component Interconnect) bus, or the AGP (Accelerated Graphics Port) bus, but modern cards almost exclusively use the PCI-express interface. PCI-express offers greater bandwidth over the older interfaces, which means that the Video Card can communicate with the CPU much faster. There are two versions of the PCI-express interface: version 1.1 and version 2.0. Newer cards are meant to run in PCI-express 2.0 slots, but the interface is backwards compatible, which allows PCI-express 2.0 cards to run in version 1.1 slots and vice-versa.
Video cards communicate with your computer through a few possible interfaces. Older Video Cards used the PCI ( Peripheral Component Interconnect) bus, or the AGP (Accelerated Graphics Port) bus, but modern cards almost exclusively use the PCI-express interface. PCI-express offers greater bandwidth over the older interfaces, which means that the Video Card can communicate with the CPU much faster. There are two versions of the PCI-express interface: version 1.1 and version 2.0. Newer cards are meant to run in PCI-express 2.0 slots, but the interface is backwards compatible, which allows PCI-express 2.0 cards to run in version 1.1 slots and vice-versa.