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Central Processing Unit (CPU)
Graphics Processing Unit (GPU)
Accelerated Processing Unit (APU)
Neural Processing Unit (NPU)
Key Takeaways
- CPUs are the core computing processors in a computer, handling everything from loading the OS to running heavy operations like gaming.
- GPUs improve video performance by offloading graphics tasks from the CPU, which is especially important for gaming and video playback.
- APUs combine CPU and GPU on a single chip to improve efficiency, while NPUs are special chips for AI and ML workloads.
Knowing the difference between the CPU, GPU, APU, and NPU is a considerable advantage when buying a new computer. It could even save you money. This is especially true if you plan to build your PC.
The four technologies are often grouped but perform separate roles. So, what exactly is the difference between a CPU, GPU, APU, and NPU?
Central Processing Unit (CPU)
The central processing unit, or CPU, is the main brain of the computer. In early computers, the CPU was spread across multiple chips. However, to improve efficiency and reduce manufacturing costs, the CPU is now contained on a single chip. These smaller CPUs are also referred to as microprocessors.
Reducing the CPU's footprint has also enabled us to design and produce smaller, more compact devices. Desktop computers can be found as all-in-one devices, laptops continue to get thinner yet more capable, and some smartphones are now more powerful than their traditional counterparts.
The CPU performs the core computing processes for your computer. Instructions stored in your device's RAM are sent to the CPU for execution. This is a three-part system consisting of Fetch, Decode, and Execute stages. Broadly, this means receiving inputs, understanding them, and creating the desired output.
Using this, your CPU aids everything from loading your operating system to opening programs and even performing spreadsheet calculations. Resource-heavy operations like video games place the most significant load on your CPU, which is why benchmarking tests are usually performed against gaming standards.
CPUs are available in many variants ranging from energy-efficient single-core chips to top-performance multicore chips. Intel uses its Hyper-Threading technology to make a quad-core CPU act as though it is an octa-core. This helps to squeeze the most power and efficiency from your CPU.
If this has piqued your interest in learning more, check out our guide to the CPU and its functions.
Graphics Processing Unit (GPU)
For all the advances made with CPUs, they still have shortcomings, namely, graphics. CPUs take input and work through it in linear steps. However, graphics processing requires multiple data to be processed simultaneously. The Graphics Processing Unit (GPU) reduces the strain on the CPU and improves video performance.
Most computers and laptops are equipped with a CPU and GPU, but this isn't always the case. Sometimes, especially at lower price ranges, your computer will come with integrated graphics instead of a dedicated GPU. If you aren't sure which setup you have, take a look at our comparison between integrated and dedicated graphics cards.
The GPU and CPU perform similar functions, but the way they do it differs. The GPU's parallel structure is specially adapted for its purpose. This helps the unit achieve the billions of calculations per second required for gaming and video playback. The GPU is often situated on a separate graphics card, which also has its own RAM.
This enables the card to store the data it generates. It's also thanks to this built-in RAM that the GPU can generate a buffer, storing completed images until you need to display them. This is particularly useful when watching videos, for example.
As these cards are easily replaced, they are often seen as one of the best upgrades you can make to your computer. High-performance graphics cards usually have a price tag to match. However, there are graphics cards for cheap gaming as well, giving an option for every budget.
Accelerated Processing Unit (APU)
To reduce physical size and manufacturing costs, manufacturers combine electronic components into single chips, known as System-on-a-Chip (SoC).
In this design, all the main electronics are combined into a single die. This enabled the growth of low-cost computing devices and smartphones. Alongside these SoC designs, ARM Holdings developed ARM processors, a mobile-first processing unit.
APUs follow the same integrated circuit design philosophy of SoCs that combines multiple chips of different functions into a single chip. However, unlike SoCs, APUs combine the CPU and GPU onto a single chip to form a combined processing unit. Not only does this reduce cost, but it improves efficiency, too. Minimizing the physical distance between the two enables faster data transfer and increased performance.
As GPUs are optimized for faster calculation speeds, the CPU can offload some work to the GPU. In a separate setup, the efficiency gains from this load sharing would be undermined by the physical distance and data transfer speeds between the two. However, the APU does make these gains possible.
Despite this, an APU doesn't give the same performance as a dedicated CPU and GPU. Instead, a dedicated CPU and GPU are best viewed as a step up from APUs. This makes APUs an affordable upgrade for those looking to update their PCs.
Processor manufacturer AMD coined the term APU to help differentiate between their line of processors with an integrated GPU. However, they weren't the only ones to combine processors in this way. Intel also began to integrate the CPU and GPU, too. Despite this, Intel has never used the term APU. They always refer to it plainly as a CPU with integrated graphics.
For a more detailed breakdown, take a look at our guide to the APU and what it does.
Neural Processing Unit (NPU)
An NPU is a special processor used for handling artificial intelligence (AI) and machine learning (ML) workloads like speech recognition and object detection. NPUs can process large amounts of data in parallel, similar to a GPU, but they are better suited for AI and ML processing tasks.
Similar to how a GPU improves your device's video processing and rendering tasks, an NPU does so, but for AI and ML workloads. Besides the high processing capabilities, NPUs are better suited for AI and ML tasks because they can do so with higher efficiency and lower power consumption, unlike CPUs and GPUs.
GPUs are also being used for AI and ML processing tasks due to their parallel processing capabilities. However, NPUs are better suited due to their specialized hardware optimizations, which result in superior efficiency in neural network operations.
While an NPU might seem like a new term, these chips are already found on modern computers and smartphones. However, NPUs are gaining mainstream attention because of the AI boom. So, if you're in the market for a new PC or laptop, check out our deep dive into what an NPU is and how to compare NPU specs.
Now that we've covered the main processing units, you know there are many choices for your computer. If you opt for a separate CPU and GPU, you'll likely spend more but also gain more significant performance gains.
Selecting an APU is a compromise between budget and performance. If you're currently running with integrated graphics, an APU is a worthwhile upgrade that won't break the bank. Unlike CPUs and GPUs, you don't have much choice when selecting an NPU because it's typically integrated into the CPU, like Qualcomm's Snapdragon X Elite processors or Intel's Core Ultra processors.