Desktop computers | A buyers guide

Although laptops are becoming more and more popular for use as a main computer, desktop computers are still the best option if you have the space and don't need the portability.

The desktop computer offers more flexibility and can be upgraded much easier (and cheaper) than a laptop or notebook.
In our buying guide we list the different options available for buying your computer and the main components that go together to make a desktop computer. Along with each component is a description of what each part does as well as some information to help you make an informed choice about your needs.

Desktop computers can either be purchased "off the shelf" with predetermined specifications, or, if you buy your desktop computer from certain manufacturers, such as Dell, you can choose the specification you require.

Another purchase option is to buy the components yourself and then either assemble your computer yourself, or take advantage of the assembly services offered by some PC retailers and PC repair companies.

Whichever route you decide to take hopefully our guide will help you choose the perfect desktop computer for your needs.

Buying a desktop computer "off the shelf"

This is the simplest option and in some cases the best. The advantage of buying "off the shelf" is mainly the convenience, being able to walk into the shop, choose a computer, get home and simply plug it in.

There are always a lot of great deals available on desktop computers, with most PC retailers offering cheap "PC bundles".

These bundles can be an inexpensive way of getting a fully functional home computer system without the need to purchase certain peripherals separately.

For example, a typical desktop computer bundle may include the PC (the desktop case, monitor, keyboard, mouse), a printer and a set of computer speakers.

The main disadvantage of buying your desktop computer "off the shelf" is the fact that "what you see is what you get". If you had a certain requirement, for example a bigger hard drive, more RAM (memory), or a more powerful video card, then you would have to upgrade the PC at a later date and possibly void the manufacturer's warranty.

So the key to buying an "off the shelf" desktop computer is to ensure you get exactly what you need, hopefully with something extra.

Building your own desktop computer

build your own computer
This is probably the best choice if you need your computer to have certain specifications. It offers the flexibility of being able to choose the computer's components, which means you can spend a bit more money on the important parts and less on the components that are not that vital to your needs.

Assembling a PC is not as difficult as it used to be, but if you have no technical experience (or simply don't want to!) then the best solution is to have an experienced computer technician do the assembly and configuration. If you purchase the parts from a retailer then the chances are that they will offer some form of assembly service. If you buy your computer components online then you will either have to assemble it yourself or pay your local computer shop to put the components together.

Each individual component will come with its own warranty or guarantee, and putting the components together obviously won't affect it. The compatibility of individual components has improved over the years and coming across incompatibility issues should be a rare occurrence.

Desktop computer components

Each desktop computer, as you would imagine, is made up of a collection of individual components. Below we have listed the main components along with a description of what exactly their role is, and also the considerations needed when choosing specific components for your ideal computer's configuration.

Desktop computer case

desktop computer tower case
The computer case is an often overlooked part of the desktop computer, it is vital to get the choice of case right. It needs to be capable of accommodating all of the components and devices you need, and also have the capabilities for further expansion.

The look of a desktop computer's case may be important for aesthetical reasons, but it is better to focus on other features of the case such as the amount of free drive bays (used to accommodate DVD writers, hard drives, etc).

Another feature to look for is if the case has USB ports at the front. These are very useful for plugging in external devices such as hard drives and digital cameras. As the ports are at the front you do not have to go around the back of the PC's case every time you want to plug a device in.

Ventilation is another concern when it comes to choosing a computer case, it is always wise to have a fan inside the case (chassis fan) as well as the power supply unit's own fan. Some cases come complete with built-in chassis fans, whilst other models only have the necessary holes and fittings to accommodate any additional fans. There are many different models of chassis fan on the market yet they all have the same standard fitting and are very straightforward to install. Chassis fans are inexpensive and the cost is negligible compared to the potential cost of a component overheating and needing to be replaced.

Power supply unit (PSU)

The power supply unit (PSU) which provides the computer with power also warrants a mention, especially when it comes to the future upgradability of the machine.

Each PSU is given a particular power rating, this typically ranges from around 300 Watts through to 500 Watts and above. The more hard drives, optical drives and other components your computer has (including fans) the more power it will require.

Also, bear in mind that when you plug in an external hard drive (unless it has its own power source) or other USB-powered device, it is using your computer's power supply too.

If you are buying a complete PC then you are limited to what PSU the model features. However, if you buy your case separately or you have a choice of what PSU goes into your machine, then keep in mind any future upgrades you may be making, especially the installation of additional hard drives.

As a general rule of thumb, the following PC configuration would be more-than-happy with a 450 Watt power supply unit:
  • 2 hard drives
  • one optical drive (DVD writer or CD ROM)
  • one chassis fan
  • one CPU fan
  • one video card fan
  • one external hard drive permanently connected

For more on the PSU see our guide.

Processor (CPU)

processor cpu
Your choice of processor will basically be down to your budget but you should try and get the best that you can afford. As this is the brain of your PC, it is probably the single most important component when it comes to performance. The 2 main manufacturers of processors remain Intel® and AMD®, the difference between the two is arguable, they both offer incredible performance and good value for money.

Processor speed is measured and stated in GHz (Gigahertz), the higher this figure is, the better the overall performance of the computer will be.

RAM memory

ram memory module
A computer's RAM is measured and stated in GB (Gigabytes). The average new desktop computer will come with around 2GB of RAM, although adequate for most uses if the budget allows then a minimum of 4GB would be advisable, especially if you will be using design software or playing games.

If you are building your own computer then get as much RAM as the budget will allow, 4GB makes a PC loaded with the Microsoft Windows® operating system fly along nicely, even with demanding applications such as games or graphic design software.

Hard Disk Drive

hard disk drive
The hard drive (or hard disk) is the computer's main storage device. It is where the operating system and program files are kept, and also where your photos, documents, music, and other files will be kept unless you use external storage for your files.

Hard drive capacity is measured and stated in GB (Gigabytes) or TB (Terabytes). Modern hard drive capacities range from around 320GB through to 1TB (1 Terabyte = 1000 GB) and beyond. This means that most hard drives have ample space for the average user.

When it comes to choosing the right size hard drive for your computer, this is going to completely depend on how many files you intend to store. As a guideline, a 320GB hard drive will hold over 80,000 MP3 songs or 266,000 digital photos.

Another consideration is that external hard drives are readily available and not that expensive. So don't put too much emphasis on the hard drive's capacity (unless you need the space), if you have the choice go for a computer model with a better processor, rather than the model with the massive hard drive.
For more on hard drives see our guide.

Video Card (graphics card)

video card
The video card creates and controls the image that is displayed on your monitor's screen. There are 2 distinct types of video card, onboard and separate. It is important that you know which type of card that your potential desktop computer has installed.
To know the difference (and if not obviously stated) look in the computer's specifications for something along the lines of "Video" or "Graphics", for example:
  • 512MB Anytech Graphics 4827 - this implies a separate video card.
  • 512MB Graphics (onboard) - means it is an onboard video card sharing the system's RAM.
Onboard video cards are built-in to the motherboard (main circuit board) and share the RAM with the system, this can be a drawback if you don't have a lot of RAM, or if you intend to use graphic design software or play games. The amount of RAM assigned to the video card can be adjusted, but can be quite cumbersome to change.

Separate video cards are plugged into a slot on the motherboard and come with their own built-in RAM (to avoid sharing the main RAM with the whole system) which increases performance dramatically. Most modern video cards also have their own built-in fan to assist cooling as video cards can get very hot during operation.

The amount of RAM a video card has is stated in MB (Megabytes) or GB (Gigabytes), an average video card these days would boast 512MB of RAM, which is adequate for most users. However, if you are using your PC for gaming or graphic design software then you may want to look at video cards with 1GB (Gigabyte) of RAM, or above if your budget allows.

Another consideration to make when choosing a video card, or a full desktop system, is the outputs on the video card. For example, some models have an HDMI output, which you may require if you want to link your computer to your TV or other HDMI enabled screen.

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