The Podcomplex Guide To Computer Hardware

Processor (CPU)

The processor is probably the first component that you'll want to examine. The two main manufacturers of processors are Intel and AMD, and both have extensive experience in the area of CPU design and manufacture. From about 1999 until 2003 these companies were locked in a 'clock speed war' where the processor speed was used as the primary selling point for all laptop and desktop computers.

Every couple of months a new processor was released which claimed to be the fastest in the world, and the performance crown switched hands several times. However, once the 3.4GHz speed level was reached, overheating problems meant that they had to look at other ways of improving the performance of their processors, which means that it's not as easy to compare processors as it used to be.

Energy efficiency is now an important driver of the processor market, particularly for laptops. More efficient processors consume less power, which leads to greater battery life. The move to dual-core processing has greatly increased the power of computers, and quad-core processors are already starting to appear. However, the speed of the processors is still a factor to consider.

Until about the end of 2008, the Intel Core 2 Duo has been the best performer out there, and this should probably still be your starting point for choosing a new laptop. AMD processors are not too far behind, but I would only buy one now if I was on a tighter budget and couldn't get a Core 2 Duo system that met my needs exactly. If you want absolute bleeding edge power, then you can go for Intel's latest i7 range, but those are still quite expensive and generate a bit more heat - although the laptop i7 cores are modified to minimise this issue.

If you're looking at a Core 2 Duo System, you'll probably see some specs that look something like this (taken from the Dell.ie website in January 2009):

But What Do All These Specifications Mean?

The processor is the engine of your computer and is the most complicated component to assess. In this guide I'll be using specification examples from the Dell website, as this is usually a reasonable indication of what the current standards are for the overall market (at least on the Intel side of things).

As the Core 2 Duo is arguably the best price/performance candidate at the moment, this is a reasonable sample for illustrating the main things to look at when choosing a CPU. The specifications of the processor can be broken into three sections:

1. Processor Speed
2. L1/L2 Cache
3. FSB Speed

Let's have a closer look...

1. Processor Speed

If you have two processors from the same product line, the one with the higher processor speed will almost certainly be better. A dual-core processor has two processors, both of which run at the same speed. So, an Intel Core 2 Duo 1.8 GHz computer will actually have two processor cores, both running at a clock speed of 1.8 GHz.

Both Intel and AMD have many product lines with many confusing names, and different types of processors with the same clock speed can vary enormously in absolute performance terms.

For example, a 2Ghz Intel Celeron processor is not as powerful as a 2GHz Intel Pentium processor. This is largely because the Celerons have less cache (see point 2 below) and often have lower FSB speeds (see point 3 below).

2. L1/L2 Cache

The L2 cache sits beside the processor and retains data that the processor uses on a regular basis. This means that the processor doesn't have to go to the main memory (which is slower) or to the hard drive (which is a lot slower) to get the information it needs.

If you really want to know more about how it works, you can visit this page at Tom's Hardware. But when it comes down to it, all you really need to know is this: for cache, the more the merrier.

In a Core 2 Duo system, the cache is shared by two processors - so if you have 4Mb of L2 cache, each processor gets 2Mb. Athlon 64 X2 and Pentium D processors have dedicated L2 caches for each core. 4MB is a great amount of cache to have, although 2 MB is perfectly acceptable for most uses too. I wouldn't recommend going for less than 2 MB unless cutting costs is the main priority.

3. FSB (Front-Side Bus, MHz)

This isn't purely a processor feature, but it is included in the processor specifications. The front-side bus is what connects the processor and your RAM - so the faster it is, the better your system will perform.

FSB is measured in megahertz (MHz). The most common FSB spec at the moment is probably 800 MHz, but you may still see 667 MHz and 533 MHz FSB speeds. FSB speeds of over 1Ghz are also becoming more prevalent, although the new Intel i7 processors use a new architecture that doesn't require a Front Side Bus.

The Price Of The Cutting Edge

The table below shows a selection of Intel processor models, with the highest performing processors at the top. As you can see, if you want the very fastest processor then you'll have to pay a rather ridiculous amount extra for very little performance gain (prices are indicative estimates).

For example, the performance increase between the T7500 and the T7800 will not be noticed by most users, and is probably in the region of 5%. However, the T7800 costs over twice as much - so unless you really need to have the fastest machine available, you should stay in the sweet spot.

You'll notice that the price increases at a reasonably regular rate through the lower spec models, but at the top the price gaps become increasingly large. The sweet spot for processors is usually around the point at which the price difference between a particular model and the one above it becomes much greater than that to the one below.

Memory (RAM)

Random Access Memory is also referred to as system memory, and it is measured in megabytes (MB), or as is more usual these days, gigabytes (GB).

System memory has a huge impact on the performance of your computer. After the processor, it's probably the single most important component for overall system performance.

If you're buying a laptop, you'll probably want to buy it with the RAM you want already installed. In this case, you should get as much RAM as you can afford - you just can't have too much memory!

As most PCs now come with Windows 7, you'll want at least 2GB of memory. RAM is actually quite cheap, so I would say that 2GB is now a minimum recommended level for any new computer - PC or Mac, Windows or Linux. A netbook might be able to get by with only 1GB, but if you have the option to go for 2GB then you should probably take it.

However, if you're buying from Dell, it may not be worthwhile to go over 2GB, as they often charge a premium for 4GB (or more) of RAM. Sometimes, UPGRADING your memory from 2GB to 4GB in your computer's specifications can cost you significantly more that the price of 4Gb RAM bought separately.

Installing new memory in a laptop is quite easy, but does require some care. In many cases, it may be a lot cheaper to buy a laptop with a smaller amount of RAM, then buy the extra memory you need elsewhere and hire a professional to install it for you. If you install it yourself, it will definitely be a lot cheaper.

Hard Drive (Storage)

The hard disk (hard drive) is where your operating system, programs and other files are stored. There are two main ways of evaluating hard disks - by storage capacity (GB) and access speed (RPM).

Hard drives store all the information your computer needs, and the bigger they are, the more stuff you can keep on them. Laptop hard drives tend to start in the 160GB range nowadays, which is quite a lot - if you're just using it for office documents and photographs, you'll probably never even need this much.

If you're storing lots of audio files, video files or will be installing many large programs, then you can get laptop hard drives in the 200GB range.

To be honest, hard drive size isn't really a crucial factor for most people. If you don't need much storage space, even the smallest hard drive will do the trick. If you need a lot of storage space, you can get an external hard drive and put your media files on that.

Even if you don�'t need lots of storage space, you should back up everything onto an external hard drive anyway. Hard drives are prone to fail, and if you only have your data stored in one place then you are inevitably going to lose it one day.

Hard Disk Speed

The other thing to watch for on a hard drive is its spin speed, measured in revolutions per minute (RPM). Laptops tend to have slower hard drives (5400 RPM) because they require less power and make less noise when operating.

A 5400 RPM hard drive will perform perfectly well for 95% of users. If you are editing lots of audio or video, then you might want to get a 7500 RPM model, but it will decrease battery life and increase noise levels slightly.

SATA Or SSD?

There is one more thing to consider in this section - although this is not something you need to know unless you really want to be on the bleeding edge of new technologies and performance.

Most laptops still use SATA hard drives, which have moving parts. However, solid state drives are gaining popularity - these use very little energy and have no moving parts. Unfortunately, Solid State Drives do have a number of disadvantages; the biggest of these is that they are very expensive.

Although SSDs have very fast random access times - which allows your computer to boot up quickly, for example, they are still quite poor at sequential reads and writes. This means they are not so good at multimedia streaming.

Overall, there is no compelling reason to choose SSD over SATA at the moment, unless you need to have the lightest, most energy efficient laptop possible, no matter what the cost. As the technology improves, however, the drawbacks of SSD will eventually be overcome - it is likely that many laptops will come with solid state drives fitted as standard over the next couple of years.

Video Card (GPU)

The graphics card contains a graphics processing unit (GPU) which takes much of the visual display work away from the main processor. A more advanced graphics card allows more detail to be displayed on screen, and can achieve higher frame rates (faster processing). Graphics solutions come in two basic varieties: integrated or dedicated.

Integrated Graphics

This is the cheapest and most common type of graphics solution found in modern computers. Basically, instead of having a separate graphics card, the graphics processor is built into the main system motherboard. This type of graphics processor usually shares system memory with the main processor and is much cheaper to manufacture.

Such integrated graphics controllers are sometimes described as having 256MB of shared memory. On a system that has 1GB of system memory, this means that 256MB of system memory can be set aside for video, leaving only 744MB of RAM for the operating system to work with.

Dedicated Graphics

A dedicated graphics card comes with its own video RAM, which is faster than main system memory. Because the video card has its own memory, the operating system is free to use all installed standard RAM for other tasks.

The actual graphics processor on a dedicated card will also be more powerful than an integrated solution, and does not use up system resources in the same way.

Dedicated graphics cards come in a variety of performance levels, although even the cheapest dedicated card should greatly outperform an integrated solution. Graphics cards may be compared by processor clock speed, memory speed and type, amount of memory, calculations per second, frame rate or rendering rate.

Screen (Monitor)

These days, almost all new monitors will be LCD screens - the old Cathode Ray Tube technology is now largely obsolete. This is certainly a good thing, as LCD monitors consume much less energy, and take up far less space on your desk (and of course, it wouldn't really be practical to have a CRT in a laptop).

The display for your computer is connected directly to your Graphics Card - as such, the power of your GPU will determine just how much resolution you can get.

For laptops, the screen comes as part of the package, and is automatically matched to your graphics hardware. The main decision you'll have to make is how big you want your screen to be - but a larger screen means a larger (and heavier) laptop. Larger screens tend to support higher resolutions, so if you do a lot of graphics work then this might the way to go. If you are a gamer, you'll want a larger screen with a more powerful graphics card anyway, so you'll be going for at least a 15" screen, but probably a 17" screen.

For desktops, the options increase considerably. Most modern desktop video cards can easily handle running any single monitor; 24" screens are easy to find, but you can even get 30" monitors if you have the cash. Generally, a video card will have at least two outputs (though often a mix of output formats, such as D-Sub, HDMI or DVI).

This means you can connect two monitors - or even more, if you have two graphics cards. However, you'll need to make sure your video card can handle any new displays that you want to add. If you want to really increase your visual real estate, check out this guide to running two monitors from your desktop PC.

Monitor Comparison Table

Taken from the multiple monitor guide mentioned above, this is a chart which measures the relative merits of various screen sizes with regard to resolution, number of pixels and value for money.

The prices quoted here are no longer current, but they are still indicative of the sort of value scale that is involved in price/resolution. It’s also worth noting that because screen sizes are measured diagonally, going from 22″ to 24″ will increase pixel count by more than going from 19″ to 21″ will.