The Fundamentals of PC building


This article explains in simple terms the parts that are required in order to build a desktop personal computer (PC) yourself.

This information is useful for the individual who is on a budget and has access to cheap or free parts already, or someone that wants to build a unique PC for a particular purpose but lacks the appropriate knowledge.

Parts required

The following lists the basic components required to build a PC:

  • Case
  • Power supply (PSU)
  • Motherboard
  • CPU + cooling system
  • Memory
  • 1 or more hard drives
  • 1 or more optical drives
  • Monitor
  • Keyboard
  • Mouse

In addition to the above the author advises that you also obtain an anti-static wrist strap to prevent the accidental damage of any electronic component.

The case

Deciding which computer case you will need is an important first step in building your PC. Does it need to be small or large? Does it need to support a certain amount of components? Do you require a specific colour?

First you will need to decide what the intended purpose is for the PC, and where it will be located. Will it be a family PC, an office PC or a multimedia system? How many disk drives does it need? How big is the space available for the PC?

The size of a case will dictate the size of the motherboard that will fit, the size of the power supply and the amount of hard drives and optical drives that will fit.

If you are planning on building a high-end machine then you may also need to consider how you are going to keep the inside of the case cool because PCs can overheat. There are a range of options available from case fans to liquid nitrogen and water cooling systems.

The power supply unit

The Power Supply Unit (PSU) will either come with the case or will be a seperate purchase. Make sure that you chose one that will both fit in the case and has enough power, measured in watts, to power the proposed motherboard, CPU and other components. The motherboard manual will tell you what size PSU will be required.

Small cases utilise laptop-type power supplies which are external to the case and are quiet. Larger cases that require more powerful PSUs require additional cooling and room at the rear and sides of the case to permit adequate airflow.

Another consideration is the amount of connectors that a PSU has. Make sure that it has enough for all the components you want to put in the case.

Some PSUs can also power your monitor, reducing the need for two wall sockets for the PC. Make sure that the selected PSU is powerful enough to power both the proposed PC components and the monitor.

The motherboard bundle

Motherboard bundle refers to the motherboard, the CPU, the cooling system for the CPU, and the memory.

I refer to the above as a bundle because deciding on which CPU you want will dictate which motherboards are compatible, the motherboard will also dictate what memory type you can have, and the above was often sold as a bundle at computer fairs.

The brain of the computer is the Central Processing Unit, aka the CPU. These days the CPU is in the form of a large flat chip with lots of pins that slot into a socket on the motherboard, or a block that clips into a socket. These CPUs can get very hot very fast and so they need to be kept cool, so a cooling system is also required. This can be anything from a heatsink and fan to a state-of-the-art cooling system depending on requirements and budget.

The motherboard is the large circuit board that is mounted to the inside of the case via screws and mounts. Every electrical component in the PC will connect to the motherboard via a specific connector. It contains all the complex circuitry needed for the CPU to work and to be able to access the devices connected.

When selecting a motherboard, also bare in mind how many sockets and connectors you will need, and whether you want a built-in (on-board) sound card and / or network card to save on space in the case. Add-on sound and network cards tend to be better quality than those that are built-in, but if you only require the basics, built-in will save you money. Motherboards have a limited number of slots for internal devices so make sure the one you choose has enough for your needs.

Also consider how many ports you require such as USB.

The motherboard specs will tell you the type of memory you can have. You will then need to decide on how many memory modules you will need and how big each module will be. As an exaample a particular motherboard may offer only three memory module slots, and each slot can take a memory module of up to 1GB in size. So say you wanted 2GBs for now. The smaller the memory size of a memory module, the cheaper it will be. So you could fill all three slots with memory that adds up to 2GB, or you could fill up only one or two of the slots (paying a little more), while leaving a slot free for future growth.

Hard drives

Hard drives are often confused with computer memory. When we refer to storage devices in computers we are referring to where your software is stored and is still available when the computer is turned off. Computer memory is where the software is processed by the CPU. Think of a hard drive as your own personal memory where everything you have ever learned and experienced is stored. The bigger the hard drive, the more data you can store. Think of the computer memory (the modules slotted into the motherboard) as your mind, where you can retrieve data from your memory to think about it. The more memory you have the more you can think about at any one time, and the faster you can think.

Hard drives vary greatly in price so when considering which ones to get you should consider how much software you want to store, and how fast you want to be able to save and load that software.

The size of the hard drive in terms of storage size will dictate how much you can store. If you want 500GB storage space then you can buy one 500GB hard drive or two smaller sized drives that equal 500GB in total. The second option may be cheaper in terms of money, but not in terms of space required in the case, power consumption, and the amount of heat generated.

The speed of the drive is measured in rpm (how fast the disks spin each minute) and are usually available at 5400rpm or 7200rpm.

Hard drive technology has evolved over the years and you can now get hard drives with no moving parts, thus reducing power consumption requirements, noise generated, and heat output. These drives have evolved from the technology used in USB memory sticks and are known as Solid State Drives (SSDs).

Optical drives

Optical drives are storage drives that take optical media such as CDs, DVDs and BluRay discs. When choosing an optical drive select the drive that best suits your needs, such as read or write capability, speed and colour. Yes, you can even choose the colour of the front of the drive so that you can match it to the front of your case.


All monitors sold today are flatscreen so your options are generally down to size, glare, resolutions, connections, built-in extras and colour.

Monitors for desktop PCs tend to run from 15" upwards with 17" to 21" being the most popular. As costs drop, larger screens become more affordable, especially the large widescreen models. Some people prefer to have multiple monitors side-by-side, if your motherboard supports it.

Screen glare and reflections are a problem with monitor screens and various manufacturers have developed competing technology to deal with this problem. So you will probably read about how your monitor has some special technology or other to show a clearer crisp image even under bright lights. Try before you buy is my recommendation.

If you are going to play the latest computer games, watch video or work with images then a fast refresh rate and high resolutions are what you need. Also take a look at the connector types available to make sure that it supports your graphic card connector type.


Most keyboards today connect to a PC via a USB connector so make sure you have enough USB ports. You can get adaptors if required. Keyboards can be wired or wireless, but if you are not going to move your keyboard too far from your PC then avoid wireless as you will need to buy batteries.

Keyboards come in all shapes and sizes. You can get the basic office type (Chicony/Cherry), ergonomic, gaming, ones with build-in tracker pads or scroller balls, ones with extra customisable keys, and novelty ones.


The shape of the computer mouse hasn't changed much over the years. What has changed is the move from using mouse balls and mats to optical mice and, wireless mice. Like keyboards there is a wide range available and most also utilise the USB interface to connect to a PC.


The above covers the basic components required to build a PC. In addition to the above you may also want to add external peripherals such as scanners, printers, webcams, speakers, microphones, headsets, joysticks and so on. You may also want to add extra network cards, graphic cards, card readers (such as for camera memory cards) and other decices. Whatever you need make sure that your motherboard has enough slots and ports to accomodate everything, and enough power to support all your connected devices.

And finally..

The main component of any PC is not the CPU as many believe, but the motherboard. The motherboard dictates the type of CPU you can have, the type of memory you can have, how many drives can be attached internally, how many ports are available for externally connected equipment, whether you can have more than one monitor attached, and how much power is available. So make sure that you choose the right one for you!

If you have any feedback regarding this article, or you have a suggestion for a new article, or just want to say thanks for the info then feel free to drop me an email at

Article date: 25th July 2010

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