Buying a Computer

PC case

A good case can simplify the task of upgrading or servicing components - as well as making your office environment that much more pleasant. A well-designed case will offer tool-less access to the interior, will have hard drives mounted on easy slide-out trays, and use colour-coded cables for internal and external parts.

Since motherboards come in different shapes and sizes, commonly known as a form factor, so do case designs.

The most common form factor is ATX. The ATX specification not only dictates where the connectors on the back of the motherboard should be (to line up with the holes in the case), but also encompasses details such as the power supply connector. There are variations on form factors -- for example, MicroATX takes the basic ATX specification, but has fewer expansion slots to allow for smaller cases. Other motherboard formats exist. AT was the de facto standard before ATX, and NLX is used to create slimline PCs. A new size to emerge and designed to replace the ATX standard is BTX. Intel was the driving force behind this new form factor and features some radical design changes to increase cooling. Similar to the ATX variations, there are also different form factors for the BTX range such as picoBTX and microBTX.

Monitors

When PC manufacturers want to shave the price of a PC, the monitor is often the first area they address. Customers generally choose a system based on hardware specifications such as processor speed and graphics card, paying little attention to the monitor other than to note its size. This is a shortsighted approach. Since you interact with your screen more than any other part of your computer, you will soon regret any decision to opt for a poor quality display. Monitor technology does not move on as quickly as that of other PC components, so the screen is unlikely to become obsolete.

There are two main monitor types that you will come across when purchasing your PC, a cathode ray tube (CRT) or a liquid crystal display (LCD). They not only differ greatly in size and features but also in aesthetics. A CRT monitor is an analog display that produces images by illuminating phosphors with an electron beam. CRT monitors of late are being overtaken in the market by the LCDs.

What sizes do CRT monitors come in?

The two common sizes are 17in and 19in. People wanting that extra viewing space can opt for the larger 21in or even 23in screen. The most popular size is 17in and is suitable for most PC users, given that it is the entry-level size. Older monitors, such as the 15in variety, are incapable of taking advantage of the resolutions supplied by even the most basic of the modern graphics controllers. If you choose a 17in monitor, you should make sure it supports a resolution of at least 1280x1024. Many manufacturers tout higher resolutions of up to 1600x1200, but these are not particularly usable on a 17in screen and users are often happier at a resolution of 1024x768. A larger 19in monitor is usable at higher resolutions, so make sure your screen supports a resolution of 1600x1200.

Resolution?

The resolution of the monitor - which also acts as a gauge for the amount of detail a display offers - comes from the number of pixels (short for "picture elements") and lines. For example, in a CRT monitor with a 1024x768 resolution, the beam lights up 1024 pixels as it passes horizontally from left to right. When it reaches the edge of the screen, it stops and moves down to the next line. The beam repeats this process until it has passed over the 768 lines of pixels on the screen. When the beam reaches the bottom, it returns to the top and begins again. A monitor with a 75Hz refresh rate completes this round-trip 75 times per second. However, 85Hz is ideal as it reduces the flickering you get from slow refreshing monitors. Most resolutions will provide a flicker-free picture when viewed at 75Hz and above.

What are flat panel displays?

The technology used in flat-panel displays is quite complex. A liquid crystal solution is held between two sheets of polarising material. An electric current is then passed through the liquid, which makes the crystals align and act as shutters, either allowing light to pass through or blocking it. TFT (thin film transistor) is the technology used in conjunction with LCD to generate colours for flat-panel displays.

Flat-panel displays are slender and stylish and are becoming more affordable as new technologies emerge. For example, a basic 17in CRT costs around $200- $300, while a basic 17in LCD flat-panel monitor will set you back around $320 to $500. Some LCD models that cost that little bit extra may even come with integrated speakers, microphone/audio jacks, USB ports, TV Tuners and pivot functions that enable you to turn the whole display from a landscape aspect to portrait. Typically, flat-panel monitors come in sizes of 15in, 17in, 18in, 19in and 21in. The 15in models are slowly being phased out; 17in is now the entry-level size.

Response times

You may have seen a reference in LCD monitor specifications to a term called response time and wondered what it was all about. Response times refer to the amount of time it takes for the crystals in the panel to move from an on to off state.

With a higher a response time, the greater the blurring effect on bright moving images on black backgrounds. The lower the response time, the less of a blurring effect there will be on the screen. Gamers and graphics professionals tended to shy away from LCDs for this reason alone but as of late, monitor manufacturers are releasing models with response times as low as 8 or 4 milliseconds. This can be a misleading statistic though and gives only a vague idea of the screen quality; be sure to do your homework when selecting the right monitor for you.

What is DVI?

Most CRT monitors are analog, meaning that your graphics card has to convert digital data into an analog signal that can then be used by the monitor. Flat-panels are digital, so this analog signal then has to be converted back to a digital signal within the LCD monitor. This can cause setup problems and screen jitter. DVI (Digital Visual Interface) aims to overcome this problem by taking a digital signal straight from graphics card to monitor, ensuring that image quality is always clear and accurate.

Reasons for buying a flat-panel monitor

If you've got the cash to spend, the most appealing reason for buying a flat-panel monitor is space. You would be surprised how much desktop space is freed up by replacing a CRT with an LCD. Most models even feature brackets at the rear of the display to mount on a wall. They also use less electricity, emit less heat and radiation and weigh much less than CRT monitors. LCD screens also have better screen geometry. Screen geometry means that no matter where an image on your screen lies, it will look the same. In CRT monitors for example, when you view an image at the edge of the screen it can look a little distorted (for example, it may appear to be a little curved) compared to that same image sitting in the middle of the screen.

Reasons for sticking with a CRT monitor

LCD TFT devices offer excellent picture quality, eliminating some of the traditional image problems of CRTs, such as light refraction and geometric distortion. They also use less power and produce no radiation. But all these goodies come at a cost. CRT monitors are cheaper. Another advantage is that the viewable angle of the CRT monitor is much better than that of an LCD. TFT displays have slowly made in-roads on this con though and some of the latest models exhibit viewing angles on par with CRTs.

To illustrate, if you stand in front of your CRT monitor (90º) and start moving either left or right (even up or down) of it to being parallel with the screen, the image that you see on the screen will always be the same, regardless of the viewing angle. Do the same thing with an LCD screen, and as you get closer to the axis of the display on some of the cheaper models, you will find the image just drops out, giving you a black screen.

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