How Graphics Cards Works

Have you ever wondered how your computer works to produce the graphic on the screen? You probably know that the graphics card is in charge of producing those images, but how exactly does it produce those images?

Here’s an in-depth look at all of the essential components of a graphics card and how it all works.

A graphics card interface is the part of a video card that connects directly to the motherboard to allow for the exchange of information.

graphics-card-interface

The two main types of interfaces are PCI Express and AGP. (There are also ISA, PCI, and PCI-X interfaces, though they are rare and outdated.)

PCI Express

This is an upgraded version of the traditional PCI interface that utilizes many individual lanes to help streamline bandwidth at a faster rate.

Not only that, but it’s also considered to be more versatile than the AGP interface with a more efficient method of consuming power due to the simple interface.

AGP

The Accelerated Graphics Port was designed to render 3D graphics and utilizes a direct connection to the motherboard. This allows for higher clock speeds and for sending/receiving groups of data in a single transfer.

The video BIOS contains the most basic setup interface for the video card and is transferred to the computer BIOS via the graphics card’s ROM or read-only memory.

This interface includes important things like:

  • Memory timing
  • Voltages
  • Operating speeds
  • RAM

Think of the video BIOS as the beating heart of a graphics card, which serves as the foundation for the rest of the components to work.

Otherwise known as the graphics processing unit, this brainchild of the video card is responsible for rendering pixels into 2D and 3D graphics through RAM and is comprised of the following parts:

  • Graphics and Computer Array
  • Graphics Memory Controller
  • Bus Interface
  • Power Management Unit
  • Video Processing Unit
  • Display Interface

graphics-card-gpu

More specifically, the GPU applies specific details to each pixel to bring them to life. Such details include colors, textures, and patterns. It does this over and over again until all those rendered pixels form a cohesive image on your screen. (The exact number of pixels depends on your screen resolution).

Because it’s working so hard, the GPU generates a ton of heat, so it sits underneath a (huge) heatsink to help keep it cool.

While the GPU is rendering all those pixels, it needs a place to store this data so that it can display the images.

This is what the video memory is for, and it usually ranges from 1 GB to 12 GB in capacity.

There are different types of memory, including:

  • VRAM: This allows the GPU to render those pixels really fast (also known as “reading and writing”)
  • WRAM: An even faster version of VRAM
  • SDRAM: Runs at a high clock and bandwidth rate
  • SGRAM: Known for enhanced graphics performance

Video memory holds what is known as digital information, and it needs a way to send this data over to the monitor which only reads analog signals.

It’s like two people who speak completely different languages trying to communicate with each other.

This is where the RAMDAC comes in handy.

Think of the RAMDAC (which stands for Random Access Memory Digital-to-Analog Converter) as the interpreter of the graphics card world.

It converts the digital data from the video memory into analog signals to send over to the monitor.

The main difference between digital and analog signals comes down to the structure of the waves.

  • Digital – rigid, square-looking waves
  • Analog – Smooth and continuous waves

graphics-card-ramdac1

The RAMDAC takes those rigid waves and smooths them out for the monitor to understand, which creates the finished image that the GPU rendered.

Outputs are used to connect the graphics card to the display cables, which are used to transfer those digital-to-analog conversion signals that the RAMDAC is interpreting.

graphics-card-outputs

Outputs are divided into the following categories:

  • VGA: Uses an analog display signal
  • DVI: Standard digital interface to transfer pixels from the computer to the monitor
  • HDMI: Conducts both audio and visual transfers
  • Vivo: Used to connect to various multimedia devices, like TV’s and DVD players
  • DisplayPort: Connects video and display devices together

Since the GPU is the hottest part of a graphics card, it needs to stay cool to prevent overheating.

Heatsink

A heatsink takes the heat caused by the GPU and distributes it throughout the fins and away from the unit, which is usually cooled via an attached fan.

graphics-card-heatsink

Water Blocks

A water block is a way to liquid-cool your GPU by taking the heat and transitioning it from gas to cooled liquid. This liquid makes its way through insulated tubes and back down toward the GPU to be reused again.

graphics-card-liquid-cooling

Single-Slot Cooler

Lower end models are often one slot tall and generate less heat than a dual slot system. These only take up enough space for one expansion slot and are usually small in size.

Dual-Slot Cooler

Higher-end models are often built with two slots to offer better cooling. A dual-slot system is designed to push hot air through the second slot and out of your computer case.

The motherboard tells the video BIOS to boot up through the graphics card interface, which sends signals to the GPU to start rendering graphics.

As the GPU is starting to assign details to each pixel, it stores this data into the video memory, which only reads digital signals.

graphics-card-rendering

The RAMDAC converts these digital signals into analog signals for the monitor to understand and sends these waves through the outputs as a means of transfer.

Meanwhile, a cooling method, like a heatsink or water block, is used to keep the GPU from overheating since it’s doing most of the grunt work.

These are the essential components of a graphics card and how they all work harmoniously to render those high-definition graphics we all know and love.

Image Credit: Graphics Card, S3 Graphics chrome 530 GT card, Wave, EVGA GeForce GTX 590, Zalman Fatal1ty GPU cooler, CPU Waterblock HDR – Tone mapped, Mindstorm

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