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Article Source: Oxford University Computer Services Date: January 2009
This guide is intended to give a simple explanation of what to consider when buying a personal computer. The intended audience are computer novices or people who have no special interest in what goes on inside a computer, as long as it performs the tasks they need.
Key Questions to Ask Yourself
There are two important questions that must be answered before settling on a specific computer to purchase:
1. What will I use the computer for (now and in the future)?
2. What is my budget?
The Basic System
There are a few components that every computer you consider must have so it is important to understand their purpose and how the will affect the performance of the computer you buy.
The Processor or CPU
The processor is the component that performs virtually all of the computation and controls the behaviour of most of the other devices. The most common processors are Intel's Pentium and Celeron family and AMD's Athlon and Duron. The crudest measure of a processor's power is its "clock speed", given in Megahertz (MHz) or Gigahertz (GHz, 1GHz = 1000MHz). These are the figures that will appear in advertisements. Generally speaking, the faster the clock speed, the faster the computer will be. The highest speed processors available at any time tend to be disproportionately expensive, so most people tend to buy a slightly slower system.
Memory or RAM
RAM is the fast memory that the computer uses to temporarily store information for the tasks it is performing. Unlike the hard drive, RAM relies on power being supplied to retain information. When you switch the computer off the information is lost (but don't panic, it can be kept on the hard drive). The size of RAM is measured in Megabytes (Mb) and, as with processor clock speed, more is usually better.
Hard Drive
The hard drive is a magnetic storage device that can hold programs and information when the computer is turned off. Information is exchanged between the memory and hard drive according to the needs of the tasks being performed (remember RAM is fast so the processor can find information quickly there). The size of a hard drive is measured in Gigabytes (Gb) and, again, more is better.
Monitor
The monitor is the device that displays information from the computer in the form of windows, icons, images and text. There are two principal types of monitor at present: CRT monitors (the ones that look like televisions) and LCD monitors. Advertisements will quote monitor sizes which is the distance measured across the diagonal of the screen in inches and the resolution in dots per inch. Larger screens can be useful for working with graphics or for desktop publishing.
Graphics Card
The purpose of a graphics card is to present information in a visual form on the monitor of the computer. The specification of the graphics card will affect the resolution that can be displayed on the monitor and the "refresh rate" of the display. The refresh rate is the number of times per-second that the screen is redrawn - a high refresh rate produces a flicker free display.
Choosing A Type Of Computer
There are two main types of computer available on the market: IBM compatible and Apple Macintosh. They both come in two forms, desktop or laptop.
IBM Compatible
The most common computers are IBM compatible (although they may be manufactured by someone other than IBM). The advantage of choosing an IBM compatible is the range of software available and the commonality with other computers (although this is less of an advantage). The term "IBM compatible" means that the computer conforms to a de-facto standard ensuring that a range of industry standard components (eg. sound cards, graphics cards etc.) can be incorporated into the machine.
Apple Macintosh
The Apple Mac is the next most common personal computer and is manufactured exclusively by Apple. There is a smaller range of software available for Macs so make sure you check that the software you plan to use is available in a Mac version.
Desktop Versus Laptop
The major advantage of a laptop is its portability. This will be the most important factor in your choice if you need to use your computer in different locations such as libraries, at home and in the office or trains. The disadvantage of a laptop is that it is usually a lower specification for a given price and the possibilities for upgrading are more limited than a desktop. Laptops often have a shorter useful lifetime than desktops, partly due to their lower specification but also due to the fact that their nature means that they take more punishment (vibration/knocks) which can cause components such as hard drives or screens to fail.
How Powerful Should The Processor Be?
IBM compatibles come with a choice of processor types (typically Pentium/Celeron or Athlon/Duron). New machines contain a processor that is usually greater than 1GHz and can be up to about 4GHz at this time. Generally speaking, the faster the processor, the quicker your software will run, but it is not necessarily the case that an 800MHz processor will run software twice as fast as a 400MHz processor. There are bottlenecks that limit performance in other places. Dual-Core and Quad Core Processors offer more advanced processing capabilities and are ready available with most new machines.
How Much Memory Do I Need?
New machines come with at least 512Mb to 1Gb as standard now. Memory is cheap at this time so add as much as you can afford, especially if you are doing image editing. As a rule of thumb 512Mb is the absolute minimum you should be considering now but buy at least 2GB if you can afford it. Packages like Adobe Photoshop really benefit from large amounts of memory - they will run with less but try to get 1Gb or even 2Gb if you can. Memory is one of the speed bottlenecks and adding more is one of the most cost-effective ways of improving an entry-level computer's performance.
Choosing The Size Of Hard Disk
Hard disks are also cheap so buy as big as you can afford. You may find that a 180Gb disk costs hardly any more than a 120 Gb one. If you want to cut corners here bear in mind that many software packages need several hundred Mb of disk space. Add up the amount for all of the software that you are going to install and leave enough room for your data.
Typical Entry-Level Systems
A typical entry-level computer (see any Dell, Time or Tiny advertisement) will have at least a 2GHz processor, 512Mb RAM, 120Gb hard drive, 17" monitor, 48x CD-DVD RW. Often other devices will be added to the package such as a printer to make the deal more attractive. Remember that the warranty is also a part of this package and should be carefully looked at.
Extra Components
It may be necessary to add some extra components to a basic system to meet your needs. The possibilities for adding internal components to a laptop are limited by the fact that a laptop is designed to take up a minimal amount of space. Take this into consideration if you finally choose to buy a laptop - buy one with the internal components you need already installed if possible.
Sound Card
Many computers have a sound card built-in to the main system board but, if not and you want to play music or have sound for games-playing then you will need a sound card.
DVD
A DVD or Digital Versatile Disc is externally similar to a CD but it has a much higher capacity for data and can accept wider range of multimedia formats including DVD movies. DVDs can also read CDs so if you buy a DVD then there is no need to include a CD-ROM in your computer.
Recordable and Rewritable CDs and DVDs (CD-RW)
CD / DVD writers are becoming more common and the cost of recordable CD and DVD media has dropped. Recordable or re-writable CDs /DVDs are a better option for backing up your data because of their higher capacity (about 650Mb for a recordable CD and 4.7Gb for DVD) and their greater reliability. It is possible use a CD/DVD writer to copy software or music but be aware that unless the licensing or copyright specifically allows you to do so, you may be committing an offence.
Scanner
Scanners are devices for converting pictures, photographs and paper documents to a digital form suitable for storing on your computer. The most common type is the "flatbed" scanner which resembles a small photocopier. There are also slide/negative scanners which can scan the contents of 35mm photographic film but these are less common and more expensive. Many scanners come with Optical Character Recognition (OCR) software which gives them some capability to scan text from a paper document into common electronic formats such as Microsoft Word. OCR software is rarely completely accurate in recognising words so proof reading and a spelling-checker are also recommended.
Ethernet Card
An Ethernet card enables a computer to be connected to a local area network (LAN) of computers. This is a permanent connection unlike the dial-up connection through a modem which only exists as long as the telephone call is established. Many of the university buildings have LANs so check with your local IT Officer to see if you can take advantage of this.
Printer
A printer provides you with the ability to produce paper copies of documents and images. There are a large number of printers on the market to suit every budget and specification but it is possibly to group them broadly into two categories for personal users: inkjets (also bubblejets) and laser printers. Laser printers are generally faster, higher quality and cheaper to run. Inkjets are cheaper to buy at the outset, and offer colour printing, but cost more to run.
Warranty
New computers will come with a manufacturer's warranty. The level of this warranty and any associated support will vary greatly. Some manufacturers will only repair faults within a year of purchase and require the machine to be returned to the manufacturer. Others will offer on-site repair (typically for the first year). Warranty periods may be up to as much as 3 years.
It is worthwhile checking to see if anyone you know has experience of support from the manufacturer you are considering.
Upgrading Later
Choose a machine that can be upgraded but remember it is more expensive to add extras later. The most common upgrade options are a faster processor, more memory and additional hard drives. Important questions to ask are: what is the maximum processor speed that can be put in this machine? How much extra memory will it take? Most machines will take at least one additional hard drive, but ask anyway for peace of mind.
Don't Forget To Budget For Software
Check what software comes with the machine. Typically this will be at least the operating system and possibly some basic packages such as a word processor and spreadsheet. If there is a particular package that you intend to use, don't forget to add this in to the cost of purchasing. Some software you may need will be available at no charge (eg Outlook Express for email) so investigate this before making a purchase. Some software you need may be available at an educational discount so shop around before buying.
One item of essential software that you should install is a antivirus. Antivirus software is not a guarantee that your machine will be safe from attack but it will offer protection from known viruses. Make sure that you keep the disks that your software comes on (and copies of the license keys for the installation). These are as much part of your computer as any of the hardware and they are evidence that you have legal copies of the software. You will need these disks if anything goes wrong with your computer and the software has to be re-installed.
Off-The-Shelf Or Built To Specification
Computer outlets such as PC World or Currys supply ready built computers which gives you the option of leaving the shop with your computer the same day. Mail order suppliers tend to build machines to specification, allowing you to customise the machine to your requirements but the disadvantage is that there will be a build/delivery period that could be several weeks long.
Second-Hand Is An Option
Take care if you choose this route - suppliers warranties are usually no more than 3 months, Private sales are unlikely to have any guarantee. Second-hand machines are often underpowered for current software.
The Operating System
New computers typically come with the operating system pre-installed. The manufacturer may offer some choice of which operating system is installed. If you intend to use a particular software package, make sure that you choose an operating system that the package supports.
Last Words Of Wisdom
Whatever computer you buy, make sure you take regular backups of crucial data (to floppy, ZIP drive, recordable CD DVD, USB Flash Memory (Pen) drive) and make sure you update your antivirus, operating system and other software very regularly.
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