Basic Computer Components Explained

A computer is made up of multiple components that work together to function as a computer and allow you to use the computer as you are familiar with. There are different components that store information for use later, calculate answers for questions, render images onto the monitors, cool down components, or allow other components to be connected to the computer. This article will discuss the main components inside a standard tower computer, which will be similar to the components in most computers like laptops, tablets, phones, etc. I will not be talking about external hardware devices, such as monitors, mice, keyboards, webcams, etc.


The motherboard of a computer is simply a piece of printed circuit board that has integrated components or connections for other components to be connected. The motherboard is used to connect together multiple components, so they can communicate with one another. This can be thought of as the telephone lines which allow connected phones to communicate and talk to each other.

CMOS Battery

CMOS is short for complementary metal-oxide-semiconductor. The CMOS battery is a chip that is built into the motherboard which stores information. The information stored on a CMOS battery is usually the system clock, the time and date on the computer, but it can also store information related to hardware settings of the machine. CMOS batteries have a lifespan, they will usually last for the entire lifetime of the motherboard but can sometimes need replacing. The approximate estimated lifespan of a CMOS battery is around 10 years, but this can often vary.

Northbridge and Southbridge

The northbridge and southbridge are another two chips that are integrated within the motherboard. These two chips act as mediators between the other components within the motherboard. For example for the CPU to communicate with the RAM of the computer, it goes through the northbridge. All communication between components goes through these two components. Buses are used to connect the components to both the north and south bridge and to connect the two bridges together. The bus between the RAM and the northbridge bridge is called the memory bus, between the northbridge and southbridge is called the internal bus, all the buses have different names to differentiate them and to refer to what they connect together.

The northbridge connects to the CPU, the RAM, the PCI-E slots and the southbridge. The southbridge connects to everything else, including the hard drive, PCI slots, BIOS, USB, etc. The northbridge is faster at transferring information when compared to the southbridge. Therefore, it is important that the northbridge is connected to components that need faster information, such as the graphics card or the ram, these components are used regularly in the normal usage of a computer and require low latency.


The Central Processing Unit, or CPU, is often referred to as the “brains of the computer”. This isn’t entirely correct, a better analogy would be the engine of a car, it takes care of the brunt of the work within a computer. The architecture of a CPU, or the subcomponents that make up a CPU, is quite complicated but there are two main parts. The Arithmetic Logic Unit (ALU) is used to calculate answers to mathematical and comparative questions and the Control Unit is used to execute other instructions. Think of the Control Unit running the main instructions and then the ALU is used like a calculator and to compare values to one another, such as if two values are equal or one is less than another. Some CPU’s can also have an integrated graphics unit. The graphics unit, or processor, is used to render images on the screen similar to a separate GPU but an integrated GPU is usually less powerful than a dedicated or separate GPU.

When looking at CPUs within computer they will be marketed using clock speed, cores, and threads. The clock speed refers to how many cycles the processor does per second, a cycle in simple terms is when the CPU does some work. Clock speed is often measured in Gigahertz (GHz) which is the number of billion cycles per second, so a 1GHz processor can do 1 billion cycles per second. Cores within a CPU allow the CPU to run simultaneous commands, actual multitasking. Threads are similar to cores but they are not physical components, cores are physical cores as they have a hardware counter-part, threads are logical cores as they do not have a hardware counterpart. Threads also allow the computer to multi-task but it is not true multitasking, it splits the two tasks into chunks and does one chunk of each task at a time. This is called time slicing. A lot of people think the higher the numbers the better the CPU, so a CPU with a fast clock speed and more cores will be better. However, this isn’t always the case as you have to take into account the other parts of the CPU you cannot base performance just off the numbers. For example, some CPUs will be able to do more work per cycle than others based on the number of physical and logical cores. Although, it is a good starting point and can be used to compare CPUs with similar architecture.

Heat Sink

A heat sink is a piece of hardware which cools down other components. There are two different types of heat sinks; active and passive. An active heat sink will include some form of moving part, like a fan. A passive heat sink does not include any moving parts and is effectively a shaped piece of metal designed in such a way to transfers heat out of a component. Often times the CPU and GPU within a component will have some form of heat sink connected to them, as these components can get quite hot when using a computer. The north and southbridge sometimes have their own heat sinks too.


A Graphics Processing Unit, or GPU, is similar to a CPU but used for graphics processing. GPU’s have a lot more processing power than a CPU but they cannot be used as a CPU replacement. This is because a GPU is designed for processing graphics, such as geometrics and other mathematic calculations used for rendering images onto the monitor, and has a smaller instruction set than a CPU. This basically means that a CPU is more flexible and can be used for more things, such as general processing and graphical processing, whereas a GPU can only be used for graphical processing. You don’t need a dedicated GPU within a computer but you do need a CPU. GPU will also have its own in-built RAM that allows it to store specific graphical information with lower latency and without using up the system RAM.


Random Access Memory, or RAM, is used to store information on the computer. However, RAM uses volatile memory which means it is erased when the computer is turned off, it does not persist after a restart. RAM is used to store information the CPU needs to access quickly. This can be thought of as short term memory, such as storing information about programs you have open and are likely to switch between.

Hard Drive

A hard drive is another component that stores information, similar to RAM. However, the main difference between a hard drive and RAM is that hard drive is non-volatile, which means it is persisted when the computer restarts, the other difference is that it is connected to the southbridge which makes it access speed slower. Hard drives are used to store program files, operating systems files, etc. Imagine like long term memory, it stores information that may be needed later such as a file you saved to your documents. There are two main types of hard drives, a Hard Disk Drive (HDD) and a Solid State Drive (SSD). A HDD consists of physical disks whereas an SSD uses flash memory storage and has no moving parts. This can make HDD slower and more fragile than SSDs. However, SSD are often more expensive and have a limited number of writes, which means when you save new files over and over again onto an SSD.

PCI and PCIe

PCI, or Peripheral Component Interconnect, are slots on a motherboard used to connect more components to a computer. This allows components to be made by other companies without needing you to change your motherboard, and can also allow you to customise your computer using different peripherals. Similar to how a USB port can be used by many different types of devices. PCI connectors are connected to the south bridge whereas PCI Express (PCIe) are connected to the northbridge. This means if you need a peripheral to be faster then it should be a PCIe peripheral. GPUs are often connected via a PCIe slot to allow the CPU to access it faster.


A Power Supply Unit, or PSU, is an external component that connects to the motherboard and other components on the motherboard. The PSU gives the other components power and is what you plug into a wall socket to give the entire PC power. PSUs have different wattage and depending on the components within the computer will determine what wattage of PSU will be required. Each component within a computer, such as a CPU, GPU, etc, will require different wattage. It is important to get the correct wattage for a PSU otherwise the components will not be fully powered and can result in faulty hardware within a computer.

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