CPU and GPU are familiar terms for even the most novice computer users, but APU is one that you might not know. That could be by design, but APUs have come a long way since their modest beginnings.
Before we take a closer look at what an APU actually is, we will first make sure we have a precise definition of both CPU and GPU.
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Central Processing Unit – CPU
Also referred to simply as the processor, the CPU is the main governing chip in what we consider a PC. At its core, it executes fundamental arithmetic, logic, controlling, and I/O (input/output) operations assigned to it by the program.
In other words, it is a comparatively straightforward piece of electronic circuitry consisting of an arithmetic logic unit (ALU) and a control unit (CU).
The ALU is responsible for executing arithmetic and logical operations, or Boolean algebra, while the CU retrieves data from memory and supplies instructions to the ALU.
Below is a straightforward illustration of how an OR gate functions. When people say that computers are merely ones and zeroes, this is what they mean.
The CU gets information that the software controls and determines which operations the ALU must perform to give the desired outcome. The ALU then uses data kept in registers and compares them, generating a result that the CU sends to the appropriate place.
This is a greatly simplified explanation, as fully detailing what these pieces do would be veering too far away from our topic.
Today, CPUs have multiple cores and countless threads, which allows them to concurrently perform tasks that older, single-core CPUs could not.
Modern CPUs often have six or more cores (perhaps even 16 in unusual cases) which can be divided into virtual or logical cores with hyper-threading or multi-threading.
The processor’s clock speed is typically considered as the measure of the speed of tasks performed. The unit of frequency is hertz (Hz), which indicates the number of cycles done per second.
Contemporary computing has advanced to the stage where a CPUs’ rate is gauged in gigahertz (GHz), which denotes it can perform an amazing several billions of actions in merely one second.
Even if 3 gigahertz is not enough for you, most contemporary CPUs can be overclocked to utilize even more computing power. However, even the most powerful CPUs out there cannot go beyond a certain point.
The current Guinness World Record is at 8.79433 GHz, which was set way back in 2012, so it’s safe to assume that it won’t increase too much until we achieve quantum computing.
Gamers shouldn’t be too concerned about having those exceptionally high clock rates, as even mid-range CPUs will be sufficient to avoid bottlenecking when paired with a high-end or even enthusiast-class GPU.
The vast majority of mainstream CPUs are produced by AMD or Intel. Intel was considered the leader for a prolonged time until AMD introduced the world to its Ryzen CPUs in 2017, essentially revolutionizing the realm of computer technology.
Although these are broadly recognized as the top CPU manufacturers out there, it’s worth mentioning that other companies, such as IBM and Apple, also produce processors. Apple’s M1 processors are particularly remarkable.
Graphics Processing Unit – GPU
Fun fact: The term GPU was first coined by Sony when they launched their original PlayStation console in 1994.
Due to its parallel design structure, a GPU is actually more efficient than a CPU when it comes to algorithms that process large blocks of data in parallel. This is partly because CPUs are more general-purpose, while GPUs are optimized to work with specific data.
There are two main types of GPUs: specialized and combined.
With a separate graphics card, the chip is on a distinct video card that’s removable and upgradeable. It also comes with its own dedicated RAM, tailored to work better for graphics-related processes. Dedicated GPUs interface with the motherboard via the PCIe slot.
There can also be numerous GPUs connected using NVIDIA’s SLI or NVLink, or AMD’s Crossfire, but those technologies are fading out. Due to advancements in the GPU world, there is no longer any authentic need for a dual-GPU setup for gaming.
Integrated GPUs are exactly what their name suggests: a part of the motherboard. They use system RAM for their operations and, as a result, are often far weaker than a dedicated GPU.
There are also external GPUs, which are comparatively self-evident. They are GPUs that are outside the PC case. They connect to the PC or laptop via a mini PCIe port, ExpressCard, or a Thunderbolt port, and have begun gaining traction recently.
In most cases, they come with their own power supply unit (PSU), as laptop PSUs are rarely sufficient to support an external GPU, which is itself a massive energy consumer.
Similar to the CPU market, there are two prominent GPU manufacturers. In the past, NVIDIA substantially outperformed its rival, AMD. Since late 2020, however, that hasn’t been the case, and these two leading GPU manufacturers are finally on par.
Like CPUs, GPUs can also be enhanced if their base clock is too sluggish to fulfill your needs.
Accelerated Processing Unit – APU
So, what is an APU?
Officially known as AMD APU, this is simply a marketing term for processors that feature both the CPU and GPU on the identical die.
This may seem like an integrated GPU, but there are substantial differences. The concept of an APU was first introduced in 2006 by AMD’s Fusion project, but it wasn’t available until 2011.
The intriguing thing about the name APU is that it is HSA-compliant; this is why Intel can’t use the term for its integrated graphics chips. HSA stands for Heterogeneous System Architecture, which refers to cross-vendor sets of specifications that allow for the integration of CPUs and GPUs on the same bus with shared memory and tasks.
HSA is defined by the HSA Foundation, which was established by, you guessed it, AMD and several other corporations, with Intel apparently not included.
Intel does have its own integrated GPU line, simply known as Intel HD Graphics, but, as previously stated and mainly due to its rivalry with AMD, it cannot be classified as an APU as it does not offer HSA features.
Technically, HD Graphics is a combination of CPU and GPU on the same die, but due to pragmatic differences, they can’t exactly be considered APUs.
What makes the APU such an intriguing piece of technology is the unique way in which the CPU and GPU are combined on a single die. As such, they can share the same resources (including RAM), allowing them to use them more efficiently.
Another positive is that, in the long term, there is a noticeable power efficiency increase stemming from the sharing of resources. This is in addition to the performance velocity, as well as the decreased manufacturing cost, which means APUs have an excellent dollar value to their name.
Just like a CPU or GPU, APUs can be overclocked. This is advantageous as APUs can be limited in performance out of the box, but you probably shouldn’t expect a significant improvement when overclocking them.
Unlike the CPU and GPU, the APU’s market is more difficult to define as AMD effectively holds all the cards regarding the APU patent. APUs are often compared to Intel’s integrated graphics line because the GPU and CPU are on the same die, but APUs easily outperform anything Intel has to offer in terms of performance.
Although APUs initially hit the market in 2011, which in technology years might as well be a century ago, AMD has skillfully adapted its Ryzen processors, and their latest release Zen 3, received a very favorable reception.
At the moment, Zen 3 appears to be excellent compared to anything Intel has to offer, so it is the optimal choice.
APU Or CPU/GPU Combo?
As always, when deciding on your next tech purchases, you should accurately assess your needs and determine the intended use for the hardware. Another key point is, inevitably, your budget. Purchasing a top-shelf gaming PC is going to cost far more than an APU.
If you’re looking for a work computer and like to game casually with eSports games or independent titles, then an APU is a superb choice.
What makes the APU an outstanding option is the freedom to upgrade. In other words, you can get an APU now, and if you want to play some more graphics-intensive games in the future, you can obtain a dedicated GPU. With AMD integrating its recent Zen 3 CPUs with the RDNA 2 chips to improve them even further, that’s probably your best choice.
However, dedicated CPUs and GPUs are superior in almost any other situation. It’s ultimately too difficult for a single-die combo to compete against the separate CPU and GPU.
To put it simply, the APU is skilled in many areas but not exceptional in any, while the CPU and GPU are precise opposites.
