What Is a GPU? Graphics Processing Units Explained

The interior of a desktop PC with RGB lighting. FeelGoodLuck / Shutterstock

Computer graphics are an essential part of any modern computer system, even lightweight laptops. “GPU” stands for graphics processing unit, and it is the part of the PC responsible for the on-screen images that you see.

What the GPU does

If you only use your computer for basic functions (browsing the web or using desktop software and desktop applications), you don’t need to know more about the GPU. This is the part of the PC that is responsible for what you see on your monitor, and that’s it.

However, for gamers or anyone who does work that can be GPU accelerated like 3D rendering, video encoding, etc., the GPU does a lot more work. These people need to get the most out of their GPU, so let’s take it a step further.

The different types of GPUs

There are two main types of GPUs you can get for a modern PC: integrated and discrete. The latter has nothing to do with avoiding attention. Discreet in this sense means that it is separate or distinct.

An AMD Radeon graphics card.A discrete AMD Radeon GPU. AMD

Graphics cards are typically large, bulky components for desktops with one, two, or sometimes three fans. These cards contain the graphics processor chip, as well as the RAM to handle higher graphics loads, such as video games. Fans keep components cool.

Desktop graphics cards are among the easiest components to upgrade. All you need to do is drop the card into a PCIe x16 slot, connect a cable to the power supply (if needed), and then install the drivers.

Laptops can also have discrete GPUs. Instead of a bulky card, however, a discrete laptop GPU is just a chip soldered to the motherboard. Unlike those on a desktop computer, they are not as easy to upgrade.

A Core i7 processor installed in a motherboard socket.The Core i7-8700 processor includes Intel UHD 630 graphics. yishii / Shutterstock

Then there are integrated graphics, which are directly integrated into the processor. Not all processors have it. AMD’s Ryzen desktop processors, for example, are notorious for their lack of integrated graphics.

Intel Core desktop chips with model numbers ending in an “F” also lack graphics, as do Core X-Series processors with model numbers ending in an “X”. Since these processors do not have a GPU, they are sold at a lower price.

A processor without graphics is only suitable for desktop computers. Again, laptops come as a package, so they require a discrete GPU or integrated graphics built into the processor.

Modern processors with integrated graphics can be surprisingly powerful. Some are able to run some older AAA titles at readable frame rates when the graphics settings are lowered.

They’re an economical choice for those who can’t afford the graphics card of their dreams yet. However, anyone who wants to do serious gaming will need a separate GPU.

What a GPU does

A fantastic setting with a knight holding magical weapons in the foreground pointing to a wooden fortress wall.Middle-earth: Shadow of War WB Games

The easiest way to understand what a GPU does is to talk about video games. In a game, we can see a computer generated image of a person, a landscape, or a finely detailed model of a 3D object. Whatever we see, all thanks to the graphics processing unit.

Video games are complex businesses that require a lot of mathematical calculations in parallel to display images on the screen. A GPU is specially designed to process graphic information, including geometry, color, shading, and textures in an image. Its RAM is also specialized to hold a large amount of information going into the GPU and video data, known as a framebuffer, which is directed to your screen.

The GPU receives all the instructions for drawing images to the screen from the CPU and then executes them. This process of passing instructions to the final image is called the render or graphics pipeline.

The basic unit to start creating 3D graphics is the polygon. More precisely, triangles. Almost everything you see in a typical video game starts with a huge collection of triangles. Other shapes can also be used, but the vast majority are triangles.

These basic shapes, in addition to other lines and points, are called “primitives”. They are designed to create recognizable objects, such as a table, tree, or a helper holding a staff. The more polygons you use for an object, the more detailed your finished images can become.

Each object has its own set of coordinates to define in a scene. If a human drew a picture of a dining room, for example, we would be using our own judgment as to where the table and chairs should be, or how far those objects should be from the wall.

A computer cannot make these judgment calls and requires contact information for placement. This is one of the reasons that sometimes things go very badly in video games and you suddenly see an object in flight.

Once the scene is set, the GPU begins to determine perspective based on where the “camera” is looking at the scene. A battle on a street, for example, will look very different if your character is standing on top of a parked bus looking at the chaos instead of stealing sneaky glances while crouching behind an overturned taxi. Again, there are a lot of calculations going on to determine viewing angles.

After a little more refinement, the images get the textures, shadows, color and shadows that bring everything to life.

All of this graphics processing is happening at lightning speed, requiring heavy calculations, which is why a separate processing unit is needed in the first place.

The GPU is specially designed for graphics processing, which requires a lot of mathematical calculations done in parallel. This stronger focus on computation and parallel operations is why the early supporters of Bitcoin turned to GPU-filled platforms to generate the calculations needed to mine cryptocurrency coins. Processors, on the other hand, are not as specialized and are more versatile.

You could technically rely on a processor for the graphics, but that wouldn’t be efficient and the end result would never be so visually impressive. The processor simply does not have the resources for most games. It is already running your operating system, other programs and background processes. It also helps to run the game with physical calculations, AI operations and other tasks.

Which GPU do you need?

The Alienware m15 gaming laptop with a Halo image displayed on the screen.Alienware

You now know the basics of what a GPU does and the different types that exist. So how do you know which one you need? If you play games on a desktop, you need a graphics card, and there are a whole world of reviews to help you choose the best one.

As a general rule of thumb, make sure you get a graphics card that is suitable for your monitor’s resolution, such as 1080p, 1440p, or 4K. The functionality of video games is constantly evolving and requires new hardware. This means that graphics cards tend to get obsolete faster than other components. Desktop computer owners should buy something that has been released within the past two to three years.

To play on a laptop, be very, very careful. Many gaming laptops have discrete GPUs that are up to two generations old and cost as much (or nearly as much) as a laptop with a newer GPU.

If you are focusing on avid video editing, a powerful processor is more important, but a discrete graphics card (even a few generations old) is also needed.

For everyone, the integrated graphics will do the trick. You don’t need a graphics card for video streaming, basic web games, or even basic photo editing. Just make sure your CPU has a built-in GPU. Otherwise, you might have a frustrating surprise when trying to start this new desktop version.

If you are curious you can check which GPU you have in your Windows 10 PC.

RELATED: How to check which graphics card (GPU) is in your PC

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