What difference does a good graphics card make?

A graphics card or a video card is basically an expansion device which is used for processing the graphical information which is used for delivering the output images. Many graphic cards offer various functions which include high speed rendering of 3D graphics and also 2D scenes. The graphic card also performs functions like decoding of video content.

Many motherboards have basic graphic cards soldered on to them to perform basic functions like producing the monitor output. Anyways, all the motherboards have expansion slots for connecting the external graphic card or other devices. The onboard graphics processor possesses a very little amount of memory and uses systems RAM to render graphics content. Modern graphic cards have evolved in to gaming devices which enable the processing of high quality 3D graphics to offer a smooth gaming experience.

A graphic card consists mainly of the following components:
Processing Unit: Also known as GPU (Graphics processing unit), this is responsible for all the processing involved in accelerating graphics. These processors are specifically optimized to perform 3D Floating point operations which are basic for 3D and 2D graphics. A GPU is characterized by its clock speed or core speed and the number of pipelines. Latest GPUs are parallel and they have higher processing power than many CPUs.
Memory: This can range from 128 MB to 8 GB in modern graphic cards. This memory is a high speed memory module as the GPU and Other components of graphic card use it. Typically, it can be DDR or GDDR. GDDR is graphics optimized DDR memory and is used in almost all the desktop video cards. DDR memory is used in mobile graphic cards due to the thermal and electrical limitations.
Video BIOS: This is another chip which contains the instructions for the graphic card’s operation. It also has information useful for the system to interact with the graphic card. This part is usually hidden and is different for different type of graphic cards. It determines the clock speed and sometimes also has functionality to overclock the graphic card.
RAMDAC: It stands for Random Access Memory Digital to Analog converter. As the name implies, it converts the digital output in to analog signal for use by output devices. Depending on the number of bits used and the RAMDAC-data-transfer rate, the converter will be able to support different computer-display refresh rates.
A graphic card generally has outputs which contain an analog output and a digital HDMI output. In the current market, AMD acquired ATI and NVIDIA are two world gaints in production of graphic processing units. AMDs Radeon 69XX series are some of the fastest graphic processing units available in the current market.