The video card (also known as graphics Card) is an expansion card that allows the computer to send graphical information to a video display device such as monitor.
How many graphics cards do you need?
As you know, future games will require more processing power, so if you just want to play games at lower resolution (i.e. 1024x1280 and lower), only one mid-range graphics card would be enough but if you are going to play games at higher resolution (i.e. 1680x1050 and higher), you may need minimum two mid-core graphics cards in SLI or Crossfire configuration or one high-end Dual-GPU* graphics card to play games smoothly.
* Some graphics cards have dual-GPU paired in one board. These cards are very expensive and usually produce more noise and heat than it's equivalent single card in Crossfire or SLI configuration.
When shopping for a graphics Card, some important factors should be taken into consideration, such as:
Type of Interface:
There are two different types of interface to connect a graphics Card to a motherboard, through an AGP slot (Max. x8 Speed) or a PCI Express (Max. x16 Speed) slot. AGP (Accelerated Graphics Port) has been the standard for a long time, but now the new PCI Express technology has taken over the scene, as it has a higher bandwidth and data transfer rate than AGP. The new PCI Express 3.0 interface can transfer the data at theoretical speed of 16GB per second.
VRAM Size and Bandwidth:
Generally the more the Video RAM the more the performance at higher resolutions. We recommend you to buy a graphics Card with minimum 1GB of GDDR3 VRAM. Some new graphics Cards are equipped with 384-bit GDDR5 memory interface.
Latest DirectX/OpenGL Support:
DirectX is a collection of application programming interfaces (APIs) for handling tasks related to multimedia. OpenGL (Open Graphics Library) is the industry standard for high-performance video, and is supported on Windows, Mac, and UNIX machines, as well as on many industrial and other specialized devices. The new graphics Cards support DirectX 11.1 and Open GL version 4.3, so they can take advantages of new game features.
The clock speed of a GPU (Graphics Processing Unit) determines the number of pixels it can process per cycle. But just like CPUs, the numbers can be a little misleading. A faster clock speed does not always result in better performance.
The fill rate of a video card is the speed at which pixels are drawn onto screen memory. It's usually measured in millions of pixels per second, and is an important measure of a graphics processor's performance. The best gaming video cards on the market have pixel fill rates as fast as 15 billion pixels per second.
The speed and efficiency of the GPU isn't the only thing that counts. The latest 3D games and software make use of advanced 3D rendering effects* such as anti-aliasing, anisotropic filtering, Tessellation, Depth Of Field, pixel shader and much more.
* If you enable features mentioned above in a game and your graphics card doesn't support those features, you will experience a significant performance loss, or at worst the game won't run at all.
HDMI (High-Definition Multimedia Interface) is a higher-definition output used with newer monitors and some high-end TVs. HDMI combines digital audio and digital video in one connector. DVI (Digital-Visual Interface) transmits both digital and analogue video (DVI-I connectors). Connecting your monitor via HDMI offers better image quality than the standard VGA connection.
DisplayPort also transmit both audio and video signals, some new graphics cards and monitors support this interface and it can be used as an alternative to HDMI.
Dual Monitor Support:
If you want to split your video output across two monitors, you will need dual monitor support on your graphics card. This feature is useful for developers, engineers, designers, and gamers.