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What's the difference between a CPU and a GPU?
When it comes to understanding the key components of modern computing, the central processing unit (CPU) and the graphics processing unit (GPU) are two very important aspects. Both play integral roles to your computer, but their functions and optimizations differ significantly, catering to various tasks and applications.
Best CPUs in 2024
Trying to build your next PC for gaming or work? Here are the best CPUs you can buy for a new machine or if you're looking for an upgrade.What is a CPU?
The brain of the computer
The CPU, to put it simply, is typically referred to as the brain of the computer. It handles most of the processing tasks within a system and can execute instructions from both hardware and software, enabling the smooth operation of the operating system, applications, and user commands. CPUs are designed with a relatively small number of powerful cores, typically ranging from 2 to 16 in consumer-grade processors. There are some that buck this trend though, like AMD's Threadripper and high-end server CPUs.
In a CPU, cores typically operate at high speeds and can exceed 3 GHz. CPUs excel at sequential processing and are versatile, making them suitable for a wide array of general-purpose computing tasks. Even nowadays, a lot of AI tasks are still placed on the CPU as CPUs are incredibly fast for general-purpose processing. The only downside is that they have a limited number of cores and can typically only process a small amount of information per cycle, it's just that those cycles are incredibly frequent.
What is a GPU?
Thousands of small cores
In contrast, GPUs are specialized for rendering images, video, and animations, making them incredibly important for gaming, video editing, and scientific computations. GPUs boast a large number of smaller, less powerful cores, and modern GPUs can feature thousands of these cores. For example, Nvidia's RTX 4090 has 16,384 CUDA cores. This is also why you may see a CPU has integrated graphics instead of doing graphics directly on the CPU, as doing graphics directly on the CPU is nearly impossible. That's not to say you can't do it, but you really shouldn't.
With that said, each core in a GPU operates at a lower clock speed compared to a CPU, and the sheer number of cores enables GPUs to handle many operations simultaneously. This parallel processing capability makes GPUs particularly effective for tasks that can be divided into smaller, concurrent operations, such as rendering graphics or performing complex calculations in machine learning and simulations. These are typically made up of matrix calculations and the like, which are complex mathematical equations but are still ultimately easy to do for a computer in isolation.
This high core count is why you'll often see AI workloads aimed at GPUs instead of being run on CPUs or NPUs because a high-end GPU can do thousands of parallel operations at once. That's also why GPUs are incredibly valuable in AI applications, and why companies are buying as many as they can get their hands on at the moment.
Best GPUs in 2024: Our top graphics card picks
Picking the right graphics card can be difficult given the sheer number of options on the market. Here are the best graphics cards to consider.What are the differences between a CPU and a GPU?
It's more than just cores
When we talk about the differences between CPUs and GPUs, it's not just the cores that differentiate them, even if that is the biggest difference. In fact, those architectural differences extend to their memory usage as well.
In a CPU, it typically has access to large amounts of high-speed cache memory, which reduces latency and accelerates processing. This is where you'll have heard of things like L1 cache and L2 cache. GPUs, on the other hand, utilize high-speed video RAM (VRAM) optimized for managing the substantial data volumes required for rendering visuals.
This distinction in memory management clearly illustrates the difference between the two uses: CPUs handle a broad spectrum of tasks, while GPUs are fine-tuned for specific, parallelizable workloads. That's not to say GPUs don't have L1 and L2 caches, they do, but those caches on a CPU are physically closer to each other than they are on a GPU, making a CPU cache have lower latency while also being typically faster to access.
On top of that, power consumption also varies massively in these components. Generally, CPUs consume less power than high-end GPUs (unless it's an Intel Core i9-14900KS), which can draw significant power under heavy loads, such as during intensive gaming or rendering sessions. Despite this, both components are essential. CPUs act as the versatile focus of computing and GPUs are a specialized powerhouse for parallel processing.
Do you need both a CPU and a GPU?
Yes, but it's complicated
In your PC, you'll need both a CPU and a GPU, but a GPU doesn't have to be a dedicated card that you put into a PCI slot. Your CPU might have an integrated GPU that can handle basic (and sometimes more intense) graphics. In that case, you just need a CPU, but that's because a GPU is inside of your processor already. Most consumer-grade office PCs won't have a dedicated GPU, and will instead rely on Intel or AMD's integrated graphics.
In fact, pretty much all gaming handhelds rely on the integrated graphics of the CPUs that power them. You need a GPU to do even the most basic of graphics in Windows, but a "GPU" can be anything that handles graphics.
With that, the question then becomes do you need a dedicated GPU? The answer there depends on what you plan to do on your computer. If you're a gamer who wants high refresh rates and pumped-up graphics settings at large resolutions, then you'll need one of the best GPUs you can get. If you're a casual gamer though, then the question is still a bit murky. You can get by on a lot of integrated graphics options nowadays, so we recommend checking out how the hardware you're considering fares in the titles you want to play.
