What Is A CPU? And How Does It Work?

What Is A CPU
What Is A CPU?

A computer cannot function without a CPU (Central Processing Unit). In this article, we’ll look at what is a CPU and how it works while explaining the Hertz specifications and cores of processors.

What is a CPU? What is she doing?

The acronym CPU stands for ” Central Processing Unit” and is called in other languages “central control unit”. It calculates and controls all important processes while managing inputs and outputs. 

The best-known CPU manufacturers for PCs are Intel and AMD. Below is a picture of an Intel CPU:

intel cpu
A CPU from above and below – here is the Intel Core i7-6700K.

If you assemble a PC yourself, the CPU you can install will depend on your mainboard as the PIN arrangement on the underside of a CPU varies.

A CPU is about 4.5 x 4.5 cm² and sits relatively centrally on the mainboard of a PC:

cpu slot on motherboard
This is where the CPU is used. 
Image source: MSI

Tasks and functionality of a CPU

A CPU is essential for a computer to work properly:

  • The CPU calculates everything that happens in the computer.
  • If you open a program, for example, the CPU calculates its execution and when it is displayed on the screen.
  • All of this happens on the basis of mathematical calculations, which in turn are based on internal machine commands.
  • These take place in the processor’s arithmetic and control unit and are done using the binary system.
  • For example, a simple machine command would be a simple addition of two numbers.
  • For a better understanding: An Intel Core i7 5960X from 2014 clocks at 3.5 GHz and can execute 336 billion machine commands per second.
  • The more machine instructions a CPU can execute per second, the more powerful and faster it is.

Example: Print page – what is a CPU doing?

All commands that you enter on the computer are converted into a language that the PC can understand and then calculated. If you want to print out a page on your PC, for example, the following happens:

  1. You give the command to the operating system to print out a page.
  2. The operating system converts the request into a calculation and forwards it to the CPU.
  3. After the calculation, the result is sent to the printer with a command.
  4. The printer prints your page.

Depending on how many user inputs, programs, and machine commands are executed at the same time, the CPU is sometimes more or less loaded. You can display the load in the Windows 10 task manager.

windows 10 task manager
Here you can see the CPU usage of running programs.

Where are CPUs installed?

Today, almost all electronic devices such as cell phones, tablets, smartphones, or kitchen appliances have built-in CPUs that control the functions of the respective device. While Intel and AMD produce most of the CPUs in the PC sector, Qualcomm and Mediathek produce most of the CPUs for smartphones.

CPU: GHz and cores – what does that mean for performance?

Heart information explained

The performance of a CPU is specified with the clock frequency in Hz (Hertz), MHz (Megahertz), or GHz (Gigahertz):

  • A CPU with 1 GHz can process 1 billion current pulses per second.
  • To understand: Complex arithmetic tasks require several thousand current pulses.

BUT: More GHz mostly, but not always, also means “faster”. A clearer indication is the number of CPU cores.

The number of cores

The more cores a processor has, the more tasks (machine commands) it can do simultaneously per second, hence increasing performance and speed.

  • While there used to be only one-core processors (single-core), two-core processors (dual-core) followed, and now four-core processors (quad-core). Today there are also eight-core processors (octa-core). Meanwhile, AMD also offers the 32-core “Threadripper 2990WX”. So the limits do not seem to have been reached yet.
  • With multi-core processors (multi-core CPUs), the computing load is evenly distributed over all cores, which leads to better performance (e.g. in games), provided that the games are designed for multi-core processors.

With Intel processors, you can also assess the performance relatively well using the names i3, i5, and i7.

Difference between Intel i3, i5, i7 and i9

There are four categories of Intel processors, i3, i5, i7, and i9. We’ll clarify where the differences lie, how you can assess the performance of the processors based on their designation, and which processor you need for your area of ​​application.

Difference i3, i5, i7 and i9

Intel processors are named according to a very specific scheme that is similar to that of AMD processors.

Example: Intel Core i5 – 6500 T or Intel Core i7 – 7700 K.

i3, i5, i7, and i9 are the respective performance levels of the Intel processors. An Intel Core i3 is the cheapest but also delivers the lowest performance. An i9 is the most expensive but has the greatest performance. The i5 is mediocre in terms of both performance and price. The i7 processors were the most powerful Intel processors at the time, but have now been surpassed by the i9. The larger the number after the “i”, the more cores and the larger the L3 cache of the processor (usually).

But that alone is not enough to be able to assess and compare the performance of a processor.

i3, i5, i7 and i9: What does the name say about the performance?

We stay with the above example: Intel Core i5 – 6500 T

  • i5: Middle class of Intel Core CPUs
powerlowmediumhighvery high
pricelowmediumhighvery high
  • 6: The first digit of the four-digit number indicates which processor generation it is. The bigger, the newer, and more powerful the processor. 6 stands for Skylake.
DigitCPU generation
Westmere / Nehalem
2Sandy Bridge
3Ivy Bridge
7Kaby Lake
8Coffee Lake
9Coffee Lake Refresh
  • 500: The model number indicates how powerful the processor is. The larger the model number, the more powerful the CPU.
  • T: Is one of several letters that describes the special characteristics of the processor.
HHigh-performance graphics
HK (mobile)High-performance graphics, without multiplier lock
HQ (mobile)High-performance graphics, four cores
Koverclock possible
M (mobile)Mobile system (laptop & Co.)
MQ (mobile)Mobile system, four cores
S.Optimized for performance
Y (mobile)Very low energy consumption
U (mobile)Extremely low energy consumption
XExtreme platform (high-end desktop)

In order to better understand the basics, we have left out the names of the X processors in the “CPU generations” table above.

Which processor do i need?

Here we have created a table with guide values. You can orient yourself by what type of processor you need:

CPU typeSuitable for
i3Office PC: e-mail, surfing the Internet, office programs, casual games.
i5All-rounder: video editing and performance-hungry games work, but not always on high settings.
i7Top/gaming PC: video editing and rendering. 
Graphics-intensive applications and games work in high settings. 
Parallel operation of virtual machines.
i9High-end/gaming PC: anything is possible. 
Graphics-intensive applications, games, video editing, rendering, and parallel operation of virtual machines run on maximum settings.

Remember: the more powerful the CPU, the more powerful the other components should be, such as the RAM and the graphics card. Because otherwise the potential will not be used.

Comparing Intel processors

The name of an Intel processor says a lot about its performance. However, an Intel Core i3 – 7300 can be faster than an Intel Core i7 – 860. This is because the i3 as the Kaby Lake generation has already been significantly optimized compared to the first i7 generation Nehalem.

Note: Also keep in mind that you cannot install every processor on every motherboard. Every second new generation of processors at Intel usually requires a new socket. This means that you cannot install older processors on current mainboards and vice versa.