What to look for in a desktop PC

What are all the bits and pieces inside a PC, and which ones should you worry about when buying a system? Read our buyer's guide and find out.

Processor


Also known as the CPU (Central Processing Unit), the processor is where the computer does most of its work. It's also one of the keys to overall performance. The faster the processor's clock speed, which is measured in megahertz (MHz) or gigahertz (GHz), the faster it can execute instructions -- although many other factors also affect overall performance. There are several different types of processors, all available in a range of clock speeds. Budget systems rely on AMD's Duron and Intel's Celeron processors. For mid-range and high-end PCs, AMD's Athlon XP delivers the best price/performance ratio, although it can't quite keep pace with the fastest Intel Pentium 4s. The PowerPC G4 is rapidly replacing the G3 on Apple Macs. For the best value, you should pick a clock speed one or two notches below the fastest available.

Memory


This term refers to RAM (Random-Access Memory), which is where PCs store software programs and data that's currently in use. Measured in megabytes (MB), the more memory you have, the more applications and files you can work on at once. In order of increasing speed, the most common types of RAM are: SDRAM (Synchronous Dynamic RAM), DDR (Double Data Rate) SDRAM and RDRAM (Rambus Dynamic RAM). To further confuse matters, each memory type is available at different speeds, for example, PC133 SDRAM runs at 133MHz. Systems with DDR SDRAM can offer nearly the same performance as those with RDRAM at a lower price. Regardless of the type of RAM, we recommend that you get at least 256MB.

Cache


The cache is another type of high-speed memory that works to enhance the processor's performance by temporarily storing instructions and data. Generally, the larger the cache, which is measured in kilobytes (KB), the better the performance. The processor you select has a fixed amount of cache -- you can't choose this feature. High-performance processors include larger caches, which are divided into Level 1 and Level 2. For example, the Athlon XP has 384KB (128KB L1 + 256KB L2), while the latest Pentium 4s have 532KB (20KB L1 and 512KB L2).

Front-side bus


Don't let the curious name fool you. This important component is essential to speedy PC performance. In essence, the bus is a pathway over which data travels between various internal system components. The front-side bus (FSB) is the segment of the system bus that carries data between processor and memory; it generally has the greatest effect on overall benchmark performance. A system with high-performance processors and other components should also have a fast front-side bus. The Athlon XP, for example, is paired with a 266MHz or 333MHz FSB, while the faster Pentium 4 uses either a 400MHz or 533MHz system bus. In practice, the FSB will only be an issue with demanding applications, such as digital video.

Hard drive


This essential PC component provides you with space to store programs and files indefinitely -- or at least for the life of the drive. But hard drive capacity, measured in gigabytes (GB), is only one measure of drive quality. The speed at which the disk rotates, or its revolutions per minute (rpm), indicates how quickly the drive can access stored programs and files. Most users will want a 7,200rpm Ultra-ATA/100 drive, although budget systems usually come with a 5,400rpm model. Ultra-ATA is the interface that connects the drive to the rest of the PC. As far as drive size is concerned, even entry-level systems now come with hard drives that start around 40GB, but in the age of MP3s, digital photography, and home movies, we recommend at least an 80GB or 100GB hard drive.

Optical drive


This term refers to CD and DVD drives in all of their various permutations. Both drive types read data on discs in a variety of formats, and some drives can also record data, images, music or video to CDs and/or DVDs. A drive's speed ratings indicate how quickly it can perform these read and write tasks. Although you can still find bargain-basement systems with just a CD-ROM drive, we suggest that you spend the extra money (the price depends on the vendor and the model) for both a CD-RW (rewritable) and a DVD-ROM drive. That way, you can create both music and data CDs and view DVD movies. Our recommendation? Get a 24X/10X/40X (write, rewrite and read speeds, respectively) CD-RW and a 16X (read speed) DVD-ROM drive. If you're more of a power user, you can purchase a recordable DVD drive that can store up to 4.7GB of data on a disc. But beware: many of these drives create DVDs in formats that other drives and DVD players cannot read.

Monitor


In conjunction with the graphics card, the monitor determines the size of your desktop workspace and the quality of the image. A traditional CRT (Cathode-Ray Tube) monitor takes up more space but costs less than an LCD (Liquid Crystal Display), or flat-panel, monitor of the same size. An LCD is compact and consumes less energy than a CRT, but a CRT produces more accurate colours (important for professional graphics work) and handles moving images better. We'd recommend that price-conscious consumers look for either a mid-range 19in. CRT or a 15in. LCD with an analogue interface. If your budget allows, though, you're unlikely to regret buying a digital-interfaced 17in. or 19in. LCD unless your work (or play) involves extremely fast-moving graphics.

Graphics processing


Together with your monitor, the graphics processor determines the size of your desktop workspace and the quality of the image. The overall video capabilities also determine how well your PC runs games. Some budget and mainstream systems integrate video processing into their chipsets, borrowing system memory, which slows performance. For better performance, you can buy a separate graphics card with its own memory (it fits into a motherboard's AGP expansion slot). Buy a system with either 32MB or 64MB of DDR (Double Data Rate) video memory for best performance -- more if you play computer games. Companies such as nVidia and ATI currently dominate the video card market -- nVidia's GeForce4 MX and the ATI's Radeon 7500 are solid, mid-range options. But if you love computer games, you'll want the latest and greatest Radeon 9700 or GeForce4 Ti cards. If you're considering buying a PC without a separate graphics card and want to use that system for gaming, make sure that the computer has an AGP slot so that you can upgrade later. But if you're on a tight budget and don't need gaming capabilities, a system with integrated graphics should do just fine -- just make sure that you get a PC with plenty of system memory.

Audio processor


Together with the speakers, the audio processor determines a system's ability to reproduce audiophile-quality music, realistic game sound effects and surround sound for DVD movies. As with graphics, a computer can provide sound processing via an integrated chipset or a separate card in a PCI expansion slot. The latter option generally offers better sound quality and more features, as well as better performance. For the best value, look for a system that has integrated audio with Dolby 5.1 decoding built in or a Creative Sound Blaster Live! Value 5.1 card. For the best audio performance, look at Creative Labs' Audigy line, or high-end cards from Turtle Beach and Terratec.

Speakers


In conjunction with the audio processor, the speakers determine a system's ability to reproduce audiophile-quality music, realistic game sound effects and surround sound for DVD movies. Audiophiles will agonise over signal-to-noise, watts and decibels, but all you really need to know is that the price and number of components in your speaker set are reasonable indicators of quality. We recommend a 2.1 (two speakers and one subwoofer) system for general computing, but gamers and home-theatre buffs will want a 5.1-piece system for true surround sound.

Modem


Your modem lets you access email, the Internet or a network over a standard phone line. An internal 56Kbps V.90 modem is standard fare on nearly every new PC nowadays. V.90 is the name of the standard technology for transmitting data at speeds up to 56 kilobits per second (Kbps).

Network adapter


To send email, access the Internet or communicate over a local network at faster speeds (up to 10 or 100 megabits per second (Mbps) depending on the type of network), you'll need a network adapter. Even for a home system, a network card has become a must if you want cable or DSL Internet access. Budget PCs may include a network adapter on the motherboard, but most systems have a separate expansion card called a NIC (Network Interface Card). Either way, look for an adapter that supports both 10Mbps and 100Mbps speeds.

USB port


These ports provide you with a standard method to connect peripherals -- such as handhelds, digital cameras, MP3 players, printers, scanners, keyboards and mice, as well as some external drives -- to your system. A desktop PC should include at least two USB ports, but some have many more. Look for a system that has some of its USB ports conveniently located on the front panel or keyboard so that you can easily plug in a camera or an MP3 player. Most systems now ship with the 12Mbps version 1.1 of the USB standard, which suits the current crop of peripherals. For room to grow, look for a system that supports the much faster 480Mbps USB 2.0 standard.

FireWire port


Also referred to as IEEE 1394, as well as i.LINK (by Sony), this port connects certain peripherals, such as digital camcorders and external hard drives, that need faster throughput than USB 1.1 provides. Not everyone needs a 400Mbps FireWire connection today, but we strongly recommend it. If the system you choose doesn't include it, you can add an expansion card for as little as £30.

PCI slot


This standard slot lets you equip your computer with cards -- including some for networking and audio processing -- that can expand your system's features. Depending on the configuration you choose, sound cards, network adapters and other PCI cards can quickly use up your available expansion slots. If you plan to upgrade your system or add new features, look for a system with at least two free PCI slots.

AGP slot


Your graphics card uses this high-speed expansion slot to interpret and display 3D images. If your system has a separate graphics card, then it almost certainly has an AGP (Accelerated Graphics Port) slot -- PCI graphics cards still exist, but are now rare. Since AGP has its own RAM, it won't slow down your system. All you really need to know is that if you ever plan to add a graphics card to play 3D games, then your system must include an AGP slot.

Operating system


If your PC is an orchestra, then the operating system is the conductor. The operating system, or OS, performs basic tasks. For example, it recognises your input, runs all other software programs, keeps tabs on files stored on your hard drive and manages peripherals such as drives. You may end up choosing your PC by the operating system that it runs. Apple's Mac OS, now in version X 10.2 (a.k.a. Jaguar), has a much smaller share of the market than Windows operating systems and offers fewer hardware and software choices. However, it retains a loyal following with certain types of users, including design professionals and students. Microsoft's Windows XP, which you can run on all other PCs with sufficient system resources, comes in Home and Professional versions. If you're planning on connecting to a local or wide are network (for business use), consider Windows XP Professional. If you're using your machine at home, the cheaper Home Edition will do the trick. You can purchase other OSs, such as various Linux distributions, but they aren't usually offered by PC vendors.

Software


In this case, software refers to the bundled software included on your new PC. At a minimum, you need a productivity suite, such as Microsoft's Works or Office XP, or Corel's WordPerfect Suite. If you're planning on using a spreadsheet or using your software for any kind of business projects, we suggest the latter two. Some systems also include many more applications and utilities. Before you let these lists of software impress you, note that computer companies sometimes pad out their list of bundled software with freely available downloads, such as Adobe's Acrobat Reader or an MP3 player, as well as applications that are included in the operating system, such as Microsoft's Internet Explorer or Apple's iTunes and Apple iMovie.

Service and support
If something goes wrong with your system or you can't work out how to use a particular feature, customer support should be your safety net. Although you can still find PC vendors who offer three-year warranties, one-year warranties are becoming the industry standard. Ask a manufacturer or seller about its policies regarding on-site service, turnaround time on repairs and shipping and restocking fees. Look for systems that include 24/7, free telephone support for the lifetime of the system. You can generally upgrade the support options or warranty length for a fee -- something we recommend for most users.