A computer's microprocessor is usually busy with other work, so the graphics card handles this. The card has a chip called a Graphics Processor Unit, a microprocessor specialized for video calculations. The GPU lets the computer's main processor do its job, allowing the computer to run at full speed.

There fore you need a good graphics card to run with your CPU as it takes strain off of it.

The better graphics card you have the more smoothly your computer can run without taking lots of Hertz off of the CPU.

Graphics cards look like this.