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Build Your Own PC: Introduction on Building a Desktop PC & the PC Case and the Power Supply Unit

This section of this website provides all of the information required to build a desktop PC and install Windows, the latest versions of which are called Windows 8.1 (Windows 10 release date is the end of July 2015). The main sections are linked to in the first table below, which is also provided at the bottom of each page. After the introduction, which provides very useful general self-build information, all of the internal components of a PC are dealt with in detail - the case and power supply unit, the motherboard, processor and RAM memory and the storage (hard disk and SSD drives) and optical CD/DVD disc drives, etc. Note that images are only provided as illustrations where words alone don't get the job done properly. I feel certain that I would have been able to build a PC successfully for the first time using only the information provided here.

Each section of this article can have more than a single page devoted to it. For example, the Expansion Cards & Peripherals section provides self-build information on graphics cards, sound cards, keyboards, mice and printers. There is still a separate section devoted to the dial-up modem, because, in spite of the widespread availability of Internet broadband in most countries, internal and external dial-up modems are still being used all over the world, including the UK and the USA. A button is provided at the bottom of each page that takes you to the next page.

This article consists of six main sections. You can access the other five sections by clicking the links below.


I cannot be held responsible for any damage that you may cause to yourself or any computer hardware or software that may come about by your attempts to build a computer using the following information.


The person who wrote the following on a computer forum probably killed the motherboard.

"I just built a new computer and everything was working great. I decided to reroute some cables for better airflow. I unplugged the 24-pin power cable from the power supply (PSU) to the motherboard, rerouted the cable, and replugged it back in. This was with the PSU still plugged into the wall. I noticed that when I did this, my computer flashed on for half a second, the fans and everything turned on briefly and then turned back off. I didn't think too much of it until I tried turning on my computer again and realised that it wasn't working. Nothing will turn on (no fans, lights, hard drives, etc)."

Having read this article, if you are unsure about how to do anything, clear the confusion before you attempt to do anything by searching for the information you require on this or other websites, or ask for advice in relevant newsgroups, such as alt.comp.hardware.pc-homebuilt, which is available through Google Groups, or on a computer forum (web search: computer forums). Don't be afraid of being flamed by the members for being stupid, because they know what it was like to be a newbie themselves.

Useful newsgroups

Here are the Usenet groups, provided by my ISP, that I am using in December 2012 via an email program (I'm still using Outlook Express):



All of those newsgroups are not full of spam, just good problems and answers.

If you are using the information on this section of this website to upgrade a computer, as a precaution, before you make any changes to the hardware or software on the computer, make sure that you have created a restorable backup of the system (or, at the very least make copies of the data files if you have the program installation disks) in order to be able to return your system to the state it was in before an irrecoverable crash took place.

Click here! to go to the section of this website that deals with the various ways of creating restorable backups and system images.

Before touching electronic components, you should discharge any static electricity by touching the computer's case while the computer, which is switched off, is plugged into the mains outlet, which is also switched off. The cable and plug have an earth wire that discharge static electricity.

Never open the power supply unit (PSU) in the case, or a CRT monitor.

There are no serviceable parts in them. Only properly trained personnel should work on these components. There are high voltages inside a PSU and a CRT monitor that can kill you, even if they are unplugged! Capacitors in them can hold a lethal charge for long after they have been switched off. LCD monitors don't make use of high voltages, so aren't dangerous, nevertheless, only qualified technicians should open one up.

Sale of Goods Act (UK)

Anything that you buy in the UK, including the components bought to build a PC, are protected by the provisions of the Sale of Goods Act. You are not restricted to the 12-month statutory warranty period to make a claim. You can demand a replacement or a refund if the goods are not fit for purpose to begin with or are rendered as such within their expected life-spans. You should not accept a credit note or vouchers that allow you to make purchases. If you cannot be provided with a suitable replacement of the goods, you can demand a full refund.

Visit the PC Warranties section of this website for some very useful information on them. For example, it is now EU law that all warranties must be valid for a period of two years, not one year.

There is plenty of other information on the Sale of Goods Act on the web.

Introduction to building a desktop PC

This article deals with building a desktop PC. Relevant information concerning the various components is provided, but up-to-the-minute, detailed information on them is provided in articles devoted to them on this website. The main components are the motherboard, case, power supply unit (PSU), processor, RAM memory, hard disk drive, video/graphics card, monitor, keyboard and mouse. Click those links to visit the detailed information on them on this website.

Click here! to go to the information on printers and scanners in this article.

It is not yet feasible to build a laptop PC, because you can't buy all of the parts to assemble one. However, it has been possible to build your own desktop PC for many years. In fact, with a little knowledge, it is possible to do all of the repairs to a desktop PC yourself. If you can build a PC, you'll know how to repair a hardware failure, because the same knowledge of the components is involved. That is currently not the case if a laptop PC's hardware fails, because, being built like a Swiss watch, it has to be repaired by experienced technicians provided by its manufacturer or by a third-party company.

The motherboard you choose will come with all of the cables you need to connect all of the PC's components that connect to the motherboard. If you don't want to buy a cooling unit for the processor, buy a retail boxed processor made by AMD or Intel, not an OEM product that doesn't come in the official packaging. The processor shouldn't be less than a current dual-core processor that has two identical processing units in a single housing. You can now buy single-core, dual-core, triple-core, quad-core, hexa-core and octo-core processors that have one, two, three, four, six and eight cores respectively. It is expected that processors with 16 cores are possible.

If the case you choose comes with a power supply unit (not all of them do), you will have to buy one. Cheap cases come with cheap power supply units that are definitely not desirable, so read the reviews of a case that comes with a power supply unit before you make a purchase.

The monitor you choose will come with the cables it requires. All of these components are discussed in detail in this article. All of the assembling requires no more than a number 2 Phillips screwdriver. A pair of tweezers are handy to change jumpers or pick up loose screws and a torch is handy for looking into the case. A magnifying glass is a great help if you need to read small writing on the motherboard.

A purchased motherboard comes with an illustrated user manual the provides precise information on what goes where on it, which can also be downloaded from its manufacturer's website, usually in the PDF format.

Choosing a power supply for your self-built desktop PC is an important factor that can easily be underdone or overdone, depending on your computing needs. A gaming computer requires much more power than an office computer. A power calculator allows you to enter the components. When all of the components are entered, the calculator tells you the wattage you require, which allows you to choose a power supply that provides that wattage plus some overhead just in case all of the components are being used at the same time. The power calculator should allow for the motherboard's use of power. A good one to search the web for is the Enermax Power Supply Calculator.

Note that most desktop PCs housed in a standard ATX PC case are fully upgradable, whereas the upgradability of most laptop PCs is currently (January, 2008) very limited - you usually have to buy a new laptop if you want to have the latest hardware components or you need to run the latest software. Therefore, this section of this site provides information on how to build and maintain a desktop PC.

The most fortunate aspect of computers and computing is probably the fact that today's latest and greatest expensive PC hardware (and, to a lesser extent, software) will be available at budget prices in a year to eighteen months time, when it still has several years of useful and productive life left in it. Bear this constantly in mind when you're reading articles on computers, especially articles on how to build your own PC. There is no imperative need to buy the latest components or software...

A good way to read this Build a PC guide is to have a Notepad or WordPad open. You can then copy and paste any text or website links that you want to remember or use later, which you would then save as a .txt file (e.g., BuildPC.txt)...

Buying compatible components for a PC, assembling them correctly, installing an operating system, and getting it to run properly is becoming easier all the time as the components become more and more integrated and easy to install.

Some early (circa 2005) AMD processors can't install the 64-bit versions of the Windows 8.1 upgrade

November 9, 2013. - Note well that some computers that use early AMD processors cannot install the the upgrades of the 64-bit versions of Win8.1 and Win8.1 Pro, but there are no issues if the user is installing the 32-bit versions. The following page provides information on this:

Microsoft confirms some older AMD processors do not support Windows 8.1 -

Using an OEM licence of Windows 7 in a PC that you have built for your own use

Can I build my own Win7 PC with an OEM version? -

The confusing myriad of cables that computers use

The myriad of cables that are in use are often very confusing to the home computer user. The following link provides a slide show of the cables and information on what each cable is used for that should dispel most of the confusion.

A World of Cables, Unknotted [Slideshow of all the cables used with a computer] -

Here is another similar page that goes through every possible type of connector:

Pictorial guide to PC sockets and cables -

Case modding

Case modding is term used to describe adding all kinds of fancy add-ons and gizmos to a computer case. You can add fancy coolers, fans, fan controllers, neon lights, etc., and you can buy fancy cases that have exotic features such as see-through areas so that you can see inside the case, etc.

Website that specialise in case modding can be found by using a web search query such as case modding uk or just case modding forums.

It is especially easy to build a computer with a new motherboard and installing Windows XP Home or Professional Editions, or Windows Vista Home Basic, Home Premium, or Ultimate Editions, or Windows 7 Home Premium or Ultimate Editions, because, apart from installing the hardware in the case and connecting the monitor, Windows configures the hardware automatically most of the time.

You can visit the Using Windows Vista section of this site for more information on the latest versions of Windows.

You can visit the Windows 7 section of this website for information on how to use, install, repair, restore, recover those versions of Windows.

Why? - Because Windows 95/98/Me/2000/XP/Vista and Windows 7 are all Plug and Play (PnP) operating systems that detect PnP devices and load their software drivers automatically - most of the time - either from within Windows itself, or from a CD/DVD, flash drive, or floppy disks.

The Plug and Play abilities of Windows XP Home and Professional Editions and the versions of Windows Vista and Windows 7 for the home user are particularly good.

I installed the components for a computer by just fitting and cabling them correctly, placed the Windows 7 Home Premium DVD in the CD/DVD drive (most home users don't need a higher version, such as the Professional and Ultimate versions), and the system was up and running in less than half an hour. There were a few devices categorised as Other devices in the Device Manager that had yellow exclamation marks beside them, which signalled that the devices hadn't been installed properly, but these were sorted out automatically by removing them and then installing the drivers that came on a CD supplied with the motherboard. After doing that, I downloaded and installed the latest device drivers for the motherboard, video/graphics card, sound card, which were obtained from the websites of the manufacturers of the devices.

No jumper or DIP switch settings were required for the motherboard because the BIOS setup program took care of all of the settings for the hardware (processor, RAM memory, etc.) automatically. All new motherboards are now mostly configured via the BIOS. A jumper on the motherboard is still used to reset the BIOS, usually to remove a forgotten security password or incompatible setting that has rendered the computer unbootable, but it has been many years since I saw a motherboard that used DIP switches for configuration.

Important BIOS settings

The BIOS is given its own section in most motherboard user manuals where the settings themselves are explained briefly. Information on how to reset the BIOS settings, password, replace the BIOS battery, etc., is also provided. If you didn't buy a new motherboard to build a PC or you bought one second-hand, if you can identify the make/model of the motherboard all you have to do is visit the manufacturer's website, search for the specific board and download a manual, usually made available in the PDF format.

The setting enabling PnP (Plug-and-Play) is usually found in the PNP/PCI Configuration page of an Award BIOS setup program, and the PCI/Plug and Play Setup page of an AMI BIOS. The setting is called PNP OS Installed in an Award BIOS, with the Yes setting enabling it and the No setting disabling it. It is enabled by default.

The Reset Configuration Data setting only works once when enabled, and then disables itself. It allows the system to clear the BIOS configuration settings and reverts them to the default settings. It's useful enabling it and disabling PNP OS Installed if the Device Manager signals an IRQ problem with a device, because the BIOS will sort the configurations out instead of Windows and the system's IRQs will be reassigned. Afterwards, you should re-enable PNP OS Installed.

With a Windows 95/98/Me/XP/Vista/7 operating system installed, it is best to have the PNP OS Installed setting enabled, but the system will work with it disabled. - Consult your brand-name computer's or the motherboard's user manual for information on the settings of the system's BIOS. (If you don't have a copy, download one from the PC's or motherboard's website. The manuals are usually in the PDF format that requires a free PDF reader.) If you're having trouble installing hardware on a Windows XP or Windows Vista or Windows 7 system, experiment with this BIOS setting. If it's disabled, the BIOS takes over from Windows in setting up the hardware.


You can purchase all of the items that make up a PC, often at bargain prices, new and used, on auction sites such as eBay. Visit the PC Purchase Check List page if you want to read an article called Using eBay safely.

Take care not to fall for scams such as Windows XP SP3/Windows Vista SP2/Windows 7 or MS Office 2007 going for £10 each, with their Product Activation disabled. If the con artist says that it is a restorable back-up on CD, it would be restorable on the machine that created the backup running the same back-up program from an installation of Windows (in a different folder from the default C:\Windows folder that the backup will create and use), but would require a Product Re-Activation on a different PC running the same backup program, because the XP, Vista and Windows 7 products take a snapshot of the system in order to prevent themselves from being copied to unlicensed systems. A back-up would contain that snapshot of the system on which it was created, which would not match the configuration of your system, and would thus trigger the requirement for a product re-activation.

Click here! to go to a page on this site called: How Microsoft Windows XP Product Activation Works.


I will take you through the process of building a standard multimedia PC, step by step, using new components. But it would be almost as easy to build one using second-hand components.

The components are: a monitor, a case with a power supply unit - a motherboard - a processor with its heatsink and fan - RAM module(s) - a video/graphics card - a sound card with two speakers - a hard disk drive - a floppy disk drive - a CD or DVD drive - an internal modem - a keyboard - a mouse - an inkjet printer.

Using a barebones kit to build a PC

If you don't want to buy all of the components required to build a desktop PC from scratch, you can buy a barebones kit that comes as a case with some of the components already installed, such as the motherboard, processor, processor's cooler, RAM memory, hard disk drive, and DVD writer. Most barebones kits just have the motherboard and power supply installed in the case.

Note that the cases are usually small and don't have room in them for a powerful PCI Express x16 graphics card and are therefore not usually suitable for use as PC gaming machines. That said, barebones systems that are specifically designed with gaming in mind are available. Other barebones systems are designed for use as Media Center PCs.

Note also that the motherboards used barebones systems are usually non-standard (not ATX) or are customised to fit the case, making them difficult to replace if you want to upgrade. If you have bought a brand-name system (e.g., Shuttle or Asus), then you should be able to buy upgrades from the manufacturer.

Barebones systems: Small Form Factor (SFF)

Computers that use SFF motherboards, micro-ATX, customised motherboards and small square cases are often called barebones systems. You can buy them and then add the missing components, which you choose and buy yourself.

Note that a barebones system is also a term generally used to designate computers (ATX and SFF) that have only the essential components installed, such as a case with a power supply unit and motherboard. You have to buy and install the other components, such as the RAM, processor, hard disk drive, and CD/DVD/Blu-ray drive, monitor, video and sound cards, etc. You should find out which components are installed and then work out which components you'll have to buy and install before you buy a barebones system. Most of the barebones kits available in the UK only have the motherboard and the power supply installed in the case.

More than meets the Eye - Barebone PC for Quad-Core and Crossfire -,review-30107.html

Good Looks, Terrible Workmanship - 4 Barebone Cases Compared -,review-29752.html

Media Center PCs

It is now possible to build your own Media Center PC that is specifically designed to provide home entertainment, because the versions of Windows that run such a computer - Windows XP Media Center Edition 2005, Windows Vista Premium and Windows Vista Ultimate - can now be purchased on their own instead of only as part of a Media Center PC. Windows XP has a special Media Center Edition, but Media Center comes built into Vista Home Premium and Vista Ultimate and those versions of Windows 7.

Visit the Media Center PCs page on this site for information on them.

The alt.comp.hardware.pc-homebuilt newsgroup

This newsgroup enables you to read the posts on the subject of building your own computer. If your Internet Service Provider (ISP) provides it, you can easily subscribe and submit your own posts to it or reply to the posts submitted by other people.

A brief note on the monitor

Computer magazines regularly review monitors comprehensively, so I will make no recommendations other than say that you should not purchase one without a 3-year warranty. in the US offers pages that list and review the most popular desktop and notebook computers and peripheral devices, including monitors. Expert Reviews in the UK has monitor reviews on its website.

The monitor is connected to the mains wall socket and to the video card's port at the back of the computer's case. Windows loads its Plug and Play Monitor by default. But if Windows has the .inf file that contains the monitor configurations for a particular make and model of monitor in its library, you can change it in the Device Manager. Then the correct make and model of the monitor will display in the Device Manager under Monitors instead of the description Plug and Play Monitor. But, since the video card interrogates the monitor to find out its capacities in order to be able to deliver a display to the screen, the Plug and Play Monitor driver is all that is usually required to use a particular monitor.

Visit the Monitors section of this site for more information on LCD flat-panel and old-style CRT monitors.

How to make sure that you get your PC returned in the same state it was in after you send it back to the manufacturer or to a repair/upgrade shop

If you have purchased a brand-name PC or built your own, you might have to send it back to the manufacturer or to a repair shop to diagnose and fix a problem. During its stay away from home, its components could be removed and replaced with old or cheaper ones. To be able to prove that your PC is returned in the state it was in before it was sent off, you should name a note of the makes/models of the hardware components.

If you don't know the makes and models of the hardware components installed in your computer, a good free utility called the Belarc Advisor creates an analysis of the hardware and software on a personal computer that you can print out. Look for it under FREE DOWNLOAD on You would the just have to run the utility again when the PC is returned and match the two printouts to find out what has been changed.

The PC case and power supply unit (PSU)

ATX PC case with transparent side

Click here! to read the more detailed information than is provided here on PC cases and fans on this website.

The following webpage provides images of the connectors that a modern power supply unit provides.

All about the various PC power supply cables and connectors -

Since the case houses the computer's components, it is an important consideration. Cases can be purchased for as little as £15, but if it comes with a power supply unit, it will be a cheap make that you would be better off not using because cheap power supplies tend to fail and when they fail they can destroy the rest of the computer's components. A low-quality power supply can take out the other components when it fails and can be a fire hazard, so the power supply is certainly not a component that can be neglected. Power supplies are dealt with later in this article.

Even reputable case manufactures, such as Foxconn, and PC manufacturers, such as Advent, are using cheap power supplies in some of their cases and PCs.

If you buy a case that has a cheap power supply, you should replace it immediately, because cheap power supplies as well as being a danger to the other components are known to have been the cause of fires.

Cheap cases also tend to have sharp edges that can cut you when you are installing the components. They have thin walls that won't insulate the sound of the internal fans well. Make sure that the case has all of the room you need to install all of the components that you plan to install. Room for the graphics card(s), hard drives, etc.

If you want to build a mini PC, you have to buy a special small case called a mini-tower (micro-ATX) case that can only take a micro-ATX form factor motherboard. If you want to build a really small PC, you need what is called a barebones case.

The main form-factor motherboards in use are ATX and micro-ATX are fitted into mini-tower (aka micro-ATX), midi-tower and full-tower ATX cases. Both full ATX and micro-ATX motherboards are powered by ATX power supply units (PSUs).

Micro-ATX motherboards are smaller than full-sized ATX motherboards and so cannot provide as many adapter-card or RAM-memory slots, can be installed in any ATX case, but are usually installed in mini-tower ATX cases. A full-sized ATX motherboard is too large to be installed in a mini-tower (micro-ATX) case.

If you want to build a media center PC for your lounge, you need a Home Theater PC (HTPC) case, which are available in a range of sizes. Full-size cases are conspicuous and accommodate standard motherboards and components and have plenty of room for hard disk drives, etc. Small HTPC cases look like any other hi-fi component. They are not as conspicuous as the full-size cases, but their small size means that they use laptop-size optical CD/DVD/Blu-ray drives and don't have much room for additional components. Visit the Media Center PCs section of this website for more information on them.

The current standard ATX cases come in a variety of designs. Cheap cases are usually opened by removing four screws at the back of the case that allow you to remove the side panels. Some cases require that the whole plastic front, which clips on, is removed to reveal the screws that allow the side panels to be removed. Other types are designed for tool-free access, such as the cases made by Akasa. Thumbscrews that can be removed by hand can be used instead of screws that require the use of a screwdriver and the drive bays can be removable. Some cases come with a power supply included, some do not, so, if you don't want to buy a power supply, make sure that the case you choose comes with a quality unit. A cheap case will often come with an unsuitable, cheap power supply that you should replace with a unit of suitable quality and maximum power output.

Note the small size of the ATX power supply unit in the top left hand corner of the midi-tower ATX case shown below. In some cases the power supply is installed in the bottom corner at the back of the case.

Desktop PC ATX  case with motherboard , hard disk drive, sound and wireless network adapter cards installed in the PCI slots

You may have to buy a mains cable if one didn't come with the case. If you bought a case without a power supply unit, a new power supply unit will come with a mains connector. Of course, a new desktop PC comes with all of the cables it requires.

A well-designed case provides the holes that can be used to route the cables under the tray that the motherboard is fitted to and away from the fans. In a brand-name case you will find the cables tied together and routed in order to leave as much free space inside the case as possible. You should do likewise when building your own PC.

Some cases are designed for silence by providing sound-isolating foam on the side panels, which can trap heat inside the case and make it necessary to add additional fans. The best-quality cases have sound-damping that can be replaced with additional fans if required.

The power supply is small, and, as such, will allow unhindered access to the motherboard, which is fitted close to the unopened side on a tray that slides into place and which is secured by screws. All good quality power supplies are this size nowadays. Do not purchase a case if it has a large, light, square power supply, because it is likely to be cheap, old technology.

The image below shows the back view of the same ATX case. The blue analog VGA port means that the motherboard has an integrated graphics chip, so a dedicated graphics card is not necessary, but can still be installed in the free blue PCI Express x16 slot, which can be seen in the image showing the case opened. If installed, the ports of a PCI Express graphics card would appear in the top slot just above the backplate of the PCI sound card.

Back of an ATX desktop PC case showing the motherboard's ports panel and the 4 adapter card slots with two cards in the PCI slots

Note well that although a high-end graphics card, such as the AMD Radeon HD 6990 card shown below, uses only a single PCI Express x16 slot, it uses up the space of two slots. In the ATX case above, the top horizontal slot is a PCI Express x16 slot and the slot beside it is a PCI slot with a sound card installed in it (the round ports are sound card ports). The three bottom slots all apear to be PCI slots, so you would have to leave the PCI slot under the PCI Express slot free in order to install that graphics card, which is described in its specificaltions as follows on AMD's website: "PCI Express based PC is required with one X16 lane graphics slot available on the motherboard."

AMD Radeon HD 6990 showing is four DisplayPorts and single DVI-I port

The image below shows the front view of an Antec SLK1650 ATX case. You can see the power-on and reset buttons and the two 3.5-inch drive bays for devices such as a floppy disk drive. Above them are three 5.25-inch bays for optical drives (CD/DVD/Blu-ray).

Antec SLK1650 ATX case

The BTX form factor for motherboards and PC cases that was created by Intel, looked as it would replace the ATX form factor, but, to date (April, 2011), for several reasons, that has not happened.

AMD has also created its own DTX form factor, which also will not replace the ATX standard. The following article deals with the DTX form factor and also provides information on the other form factors, including BTX.

If you want to read technical information on the different form factors, visit

You can find more information on the form factors on the Motherboard, PC Cases and Power Supplies section this site. Use your browser's Back button to return to this point on this page.

It is difficult for non-specialist people to determine the quality of a particular power supply unless they rely on brand names of the manufacturers that are known to produce quality units, such as Antec and Enermax. But the well-known manufacturers are not the only producers of quality power supplies. There are many relatively unknown manufacturers that produce units of quality.

Moreover, a poor-quality power supply doesn't have to be large, it could also be as small as a high-quality unit. So, a good rule of thumb to use is this - better quality power supplies tend to be heavier than those of lower quality. If you take the power supply out of the case and weigh it, it should not weigh less than between 3 and 4lbs (1.5kg), otherwise it is probably not adequate to meet the requirements of a modern system.

If you buy a case that is cheap, it will almost certainly contain a cheap power supply unit, so never spend less than about £30/$50 on a case that has a power supply installed in it and if it is a cheap case with a power supply, search for reviews of the make/model of the power supply. (Cases that don't come with a power supply unit can be purchased.) As is the case with the RAM memory, spending as much as you can afford on a quality case could save you time locating the cause of problems and probably a small fortune in repair costs in the long run.

The image below shows an Antex Trio 430 power supply unit. The 430 means that it provides 430W of power.

Antec Trio 430 power supply unit

There is more detailed information on power supplies on the next page of this article.

Entering the following search query in a web search engine provides plenty of instructional videos on power supplies: youtube power supplies.

Static Electricity and Other Important Warnings

Electronic devices can easily be destroyed by static electricity, which can discharge thousands of volts that cannot harm a human but will be fatal to a motherboard, RAM modules, or expansion cards, so, before installing anything, you should take the precaution of discharging yourself by touching an earthed metal object, such as the computer's case, attached to a mains power outlet, with the switch turned off.

Also, never work on the insides of a computer, or plug in non-hotplug devices, such as the monitor, when it is switched on. A sudden drain of current from the motherboard can destroy it.

To hotplug a device means plugging it in when the computer is swiched on and is running. You can only 'hotplug' USB and FireWire (IEEE 1394) and SATA serial devices.

And, under no circumstances switch on a computer that has only its motherboard installed. You will burn the power supply unit out, because the power supply unit (PSU) requires a load to work, which means having at least the most basic working configuration of a motherboard, video card, processor, and the RAM module(s) installed.

The case is a neglected component

The computer's case, like the motherboard, is a neglected component. It's possible to buy a case without a power supply unit (PSU), which powers the computer, but most cases come with one, therefore care should be taken when making a choice.

The PC case with its power supply unit (PSU) are crucial components whose importance is often overlooked. This is a serious oversight, because the case (with its power supply) is as important to a PC's stability and performance as its RAM memory, motherboard and processor. The case should be well designed so that it is quiet (has no whining fans) and keeps the internal hardware adequately cooled. The case should also provide easy access to its components so that it is easy to work on.

They also come in several different sizes and types - mini-tower, midi-tower, full tower, and desktop (a desktop case lies horizontally on the desk instead of vertically like a tower case). Since most users don't require anything more than a midi-tower case, it is the type most commonly used in the construction of a personal computer.

AT cases and motherboards have been superseded by the ATX standard, which, was expected to be superseded by the BTX standard that Dell already uses for all of its Intel-based desktop PCs. However, that succession has not happened and the ATX form factor is still king.

The description of a motherboard that indicates its type is called its form factor. ATX form-factor motherboards fit inside ATX cases.

Home Theater PC (HTPC) cases, which usually lie horizontally as opposed to vertically, can usually accommodate standard ATX components, so it isn't necessary to buy specially-sized motherboards or half-height adapter (video, sound, etc.) cards.

Most of the current PC cases have some tool-free features, such as clips that retain adapter cards, thumbscrews for the side panels, and tool-free drive bays that have plastic rails that clip to the side of the hard disk drive(s) and CD/DVD drive(s).

If you read the new computer reviews in a computer magazine, such as Computer Shopper (Expert Reviews on the web), the name of the case is seldom mentioned in the articles, and is never given a reference in the comparative tables at the end of the articles. A serious oversight, because if you have a bad case with an unreliable, poor, or low-powered power supply, you have a bad system that is highly likely to be very problematic no matter how good the other components may be.

On a high-quality motherboard, there are several large capacitors that store power that is distributed to the RAM and processor as the power requirements fluctuate. But there are not as many large capacitors on economy motherboards that cost under £50/$100, so the quality of the motherboard and the power supply must be taken into account when making a decision on which make and model of both components are to be purchased.

As a crucial part of a self-built computer, you will therefore need to purchase a quality case, part of which will be a quality power supply unit (PSU).

When buying a power supply, all you have to do is to find out if it can run the type of processor and graphics card you are going to use it with and that it is a quality unit that it is relatively small compared to the inside of a midi-tower case of the kind shown below, and that it is heavy.

Quality power supplies are heavy; cheap units are comparatively light. For example, a quality 400W power supply should weigh about 1.8kg or 4lbs. The reason for the weight: the capacitors and components that deliver a quality supply of power are heavy. If a power supply designated as a 400W unit only weighs about a pound or half a kilogram, it doesn't contain high quality components and is likely to cause problems, especially when the computer is stressed and needs to draw plenty of power, or the mains supply becomes irregular.

Read the following article called, "How to pick the best PC power supply":


The image below shows the inside of an inexpensive case without any of the components installed. One of the side panels has been removed. The small power supply unit, with the various power cables coming from it, can clearly be seen in the upper left hand corner. The case fan with its cable is just below it.

Note that there are many different designs of case that can have all kinds of fancy ways of accessing them, and installing or removing the components. The case shown below is a standard case in which all of the components are screwed into it.

Inside an empty case showing the PSU  and drive bays

The drive bays are in the upper left- hand corner of the case and below them are the plugged cables that come from the front of the case for the case speaker that delivers coded beep sounds from the BIOS, the LED lights, the Reset switch, and the Power-on switch, as shown in the image below. As you can see, the plugs that fit into appropriate connection points on the motherboard are usually clearly labelled. Exactly where they are connected will be illustrated in the motherboard's user manual. An illustrated example is provided on Page 3 of this article.

Inexpensive cases that don't require any tools to install or remove the components are available, such as the ATX Raijintek AGOS Mid-Tower Chassis, which is priced at only L40 (January 2015). It does not come with a power supply.

Raijintek AGOS Mid-Tower Chassis - The plugged cables that come from the front of the case and are plugged into the motherboard

Front-mounted ports

Most current PC cases provide USB (USB 2.0 and USB 3.0) and audio ports from the front of the case that are usually concealed behind a panel. An eSata port (for an external SATA hard disk drive or CD/DVD writer) and FireWire ports provided at the front of the case were more common at one time but are now rarely provided. USB 3.0 support is now provided by most motherboards, on the main ports panel that appears at the back of the case when the motherboard is installed and USB 3.0 headers on the motherboard that connect by cables to ports on the front of the case.

In order to be used, the motherboard must provide the headers that their cables connect to but the case should but might not provide the cables. It is unlikely that the cables will be provided with the motherboard. So, if you want USB ports from the front of the case, make sure that any case you buy supplies the cables. The motherboard's user manual, which is can be downloaded from its manufacturer's site, should provide you with the information on where the headers are located on the motherboard.

If the headers are provided by the motherboard for the front-mounted ports and one or more of them don't work, check the motherboard manual for a jumper setting that enables them.

If the power supply unit fails dramatically...

If the power supply unit (PSU) fails dramatically, it can take the rest of the components to the grave with it. A cheap power supply is more likely to produce a dramatic and expensive death scene and other power problems than one made by a manufacturer of quality units.

A cheap power supply is also likely to be large and come in a badly designed case that leaves little room for movement due to the size of the power supply and other deficiencies in its design. A power supply should be a small unit that is tucked away in the top corner of the case above the motherboard's external ports, leaving access to the motherboard unhindered. It can also be located in the bottom corner at the back of the case.

If the power supply is faulty, it will be very difficult to prove that it is the source of your system's problems. Unless you have and know how to use expensive diagnostic testing equipment, you will have to have another case that works with a full set of hardware components that do not work in that case with the faulty power supply installed in it.

Even if you know that the power supply is at fault, you are likely to experience severe problems putting the situation right.

For instance, I once purchased a case that had a faulty power supply, but because I didn't return it within 14 days, it was sent to the company's service centre for repair. After a month of hearing nothing, I had to deal with the service centre at the other end of England, because the branch in my town does not deal with repairs even though that was where I handed it in. The service centre found out that the courier given the job of returning it to me had failed to do so due to the driver putting a message under the security doors at the front of my block of flats. It was left in storage for two weeks. When I got it back it was in exactly the same non-working state. Two months after I purchased the case, I finally got a refund after writing to the CEO and threatening to post my story all over the web - indefinitely.

So, do yourselves a favour, purchase your case from a local computer store that will be able to test it locally, or provide you with a replacement if the power supply fails during its statutory twelve-month guarantee period.


The following link goes to a page containing a flow chart showing the steps to troubleshoot power-supply failure:

Power Supply Failure -


If it comes with one, a quality ATX case has a small, heavy power supply unit (PSU), which leaves plenty of room to install and work on the motherboard - and the hard disk drive(s), floppy disk drive, and CD/DVD drives can be slid out of their bays instead of having to unscrew and then remove them from a fixed bay - as is the case with most cheap cases.

Showing how rails are fitted to a CD/DVD drive so that the drive can be easily removed

Hard disk and CD/DVD/Blu-ray drives can be housed in a single unit that slides out from the front of the case by removing the front panel of the case, which, when removed, allows two screws to be removed so that the side panels of the case can be slid out.

A CD or DVD or Blu-ray drive slides into a fixed bay on two rails fixed to both sides of the drive. The rails (shown in the image above) have clips on their ends that protrude out of the front of the case, thereby enabling the drive to be slid out of the front by disengaging the clips - in the same way as the whole bay for the disk drives can be removed from the front of the case , which makes installing or removing the drives very much easier than having to do so from fixed drive bays.

Some useful information

Most computer stores, retail or online, sell PC cases, but shop around before you buy, because the prices for the same goods can vary widely. Most of the hardware advertisers in a magazine such as Computer Shopper (Expert Reviews on the web), sell quality cases.

Websites such as sell quality cases, motherboards, heatsink and fan units to cool the processor, etc. This company also sells overclocked hardware that requires quality power supplies and extra cooling, so it sells everything you need to build a PC that is as well suited to overclocking as possible. Similar companies exist in the US.

Below is an image of a CoolerMaster heatsink and fan unit for an 850MHz AMD Athlon 64 processor. You must purchase a cooling unit designed for a particular make and model of processor. Some cooling units have been designed so that they fit a wide variety of both Intel and AMD processors. If buying online, the seller's information should provide the information about which socket types are supported. Otherwise, the CPU cooler's retail packaging will provided that information. The manufacture's website, if it has one, should do so as well. The cable is connected to a socket on the motherboard beside the processor.

Coolermaster heatsink and fan unit

Intel and AMD processors bought as retail packaged products usually come with a thermal paste applicator or a cooling unit that has a patch of thermal paste on the area that covers the processor that has to be uncovered before installation by removing a sticker. There is no standard way to install a cooling unit. The method is determined by the processor's socket type on the motherboard. Every new retail packaged processor or motherboard comes with a user manual that provides instructions on how the provided cooler is installed on the motherboard's socket. All of the major motherboard manufacturer's provide manuals, usually in the PDF format, that can be downloaded from their websites.

For more information on heatsink and fan units and thermal paste and thermal pads, visit the Processors pages on this website. Click here! to go directly to the information there on processor cooling.

Here is what someone had to say about using thermal paste in a purchaser- review of a heatsink and fan unit:

"The problem I encountered was that my temps were a little high, around 45C. But after some research, I found out that the thermal paste needs some time to "cure", like set into place. After a couple days the temps dropped from 45C to 40C and now they're around 33-38C degrees idle. The manufacturer who makes MX-4 (the thermal paste I used) say that it can take from 100-200 hours for the thermal paste to cure. So don't start taking your computer apart straight away if you're not getting the best temps. (It also depends on what kind of thermal paste you're using, as MX-4 is quite a thick paste, whilst others may not need a lot of time to cure). Just be sure to use a good quality thermal paste if you want the best temps."

If you don't use the stock cooler that comes with a processor, you have to buy one that is designed for the make and model of the processor. It comes with installation instructions, but if you can't make head or tail of them, try searching YouTube for a video showing how that make/model is installed. Viewing a bad video is much better than trying to follow poor instructions.

Intel Socket LGA775 processors are no longer manufactured, but they are still being used in millions of PCs. Intel still uses the same type of pushpin cooling units for its Socket LGA775 and later processors, so finding one is easy. The specifications of a particular cooler tell you which range of processors that it can be used with. Processors made by AMD and Intel use different methods of attaching the cooler to the motherboard, but, as mentioned earlier, it is possible to buy coolers that can be used with both Intel and AMD processors.

Note well that some heatsink & fan units can have some form of sticky heat transfer material on the underside of the heatsink, usually in the form of a small square that fits over the processor's central core where the main processing chip is housed. This will help the heat to conduct away from the core to the heatsink so that the fan can dissipate the heat into the case. Since it is sticky, a thin protective plastic film will have to be removed prior to fitting the cooler to the processor. Failure to do so could cause the processor to overheat rapidly enough to destroy itself.

When you purchase a retail boxed processor, it usually comes with a suitable heatsink and fan unit and instructions on how to install the processor itself and the heatsink and fan unit. You will usually have to buy your own thermal paste that is applied thinly over the top of the processor in order to make the heat transfer between it and the heatsink as efficient as possible.

Water cooling systems

Water-cooled systems have been available for some time, but it is expensive compared to using the usual heatsink and fan coolers, which is perfectly adequate for most PC owners. But, just in case you feel like going down that route, here is an illustrated article on how to install a water-cooling system:

A Beginner's Guide For WaterCooling Your PC -

Note that water-cooling systems are usually large, taking up plenty of space. Consequently you have to buy a case with sufficient space to install one. Such cases have been scarce since water-cooling devices first became available, no doubt because not many people use them. As might have been expected, since not many of them are sold, the cases capable of housing a water-cooling system are not cheap. The following article deals with the type of case that is required, ranging in price from £150 to a staggering £323:

Four ATX Cases For High-Capacity Water Cooling, Reviewed -,review-32399.html

And here is an article on hybrid coolers that are mixture of fan and water cooling:

Radical CPU Coolers from CoolIT -

PC case fans

You can also purchase additional fans to fit in the case The image below of a case fan is not of the same scale as the heatsink and fan unit shown above.

If you want a computer that is a quiet as possible, fans of 120mm (12cm/4.72") are recommended because they spin slowly compared to smaller fans and therefore don't make as much noise. If you buy a case, find out the size of its case fan(s).

I have a case which has a transparent side that has a 100mm (10cm/3.93") fan in its middle that has a blue LED light in each of its corners that cast blue light into the case. If I want to see if the processor's fan is working, I just have to look into the case. The noise the fan makes is slight. The case rests on top of a computer desk. That side of the case faces the monitor, so it blows air across the desktop, which I find refreshing, even in winter.

If there isn't a ready-made mounting position or opening, you may have to cut an opening in the case to fit a case fan, depending on how many fans are already in the case, or where in the case you want it.

Just make sure that you attach the plug to the motherboard connector the right way round. You don't want the fan to spin in reverse and suck air into the computer when you want it to expel the air. You could have a fan at the front of the case that sucks air into the case, and a fan at the back of the case that expels it. What you don't want is two fans in those positions both of which suck air into the case. The idea is to have cool air flowing over the components.

A computer case fan

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