Buying The Right Computer

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Buying The Right Computer

Make it easier to filter through the wide range of Desktop PC offerings on eBay today as I guide you through everything that you need to know about computers, what's sought after and what should simply be avoided!

Three Simple Rules

1) Cheap Hardware - Beware!

It may have saved you money initially, but you're going to regret it when it fails and you're at the mercy of the computer repair man to diagnose the problem, order the new part and install it at the risk of losing your data!

Many computers being sold on eBay sell with inadequate Power Supply Units inside them. A Power Supply Unit is something that the end user won't really notice. It's a small cuboid shaped box, inside the case at the rear. It is a transformer that converts electricity from the mains at 230V to direct current rails of 3.3V, 5V and 12V. If it's adequate it'll quietly do it's work and you'll never know it's there. If however it's a cheap unit by substandard brands such as (and among many) Qtec, Aspire/Apevia, iCute and from retailer value cases. These can often operate at low efficiencies, wasting a lot of energy as heat and noise. As the internal components degrade over time (this will happen to ALL PSU's, quality or not) they will become weaker and when they're no longer able to take the load of the machine, the computer will become very unstable resulting in restarts and random shut downs. Eventually, the PSU will fail and very often in the process, taking out other system components! This may not matter to you if the computer is within warranty but it will if it happens to cause a Hard Disk Drive failure, resulting in the loss of your data!

You needn't worry about Processors, Graphics Cards and Hard Disk Drives. The only two major desktop processor manufacturers are Intel and AMD and all CPU's are built to the same standard, whether they're £20 or £800 parts. Graphics Card wise, the sole manufacturers are ATi and nVidia, and all the Add in Board (AIB) Partners such as Asus, XFX, Powercolor, eVGA that supply these cards must comply to their minimum standards. Hard Disk Drives too aren't a concern as there are only four manufacturers that offer their Hard Disk Drives in the UK, which are Seagate/Maxtor, Western Digital, Samsung and Hitachi and they're all fine.

Memory however is a major component that come from major brands such as Crucial, Corsair, OCZ, Kingston, G.Skill and AData but also come as no name generic parts. The generic parts are arguably more likely to be faulty and this can cause problems such as the Blue Screen of Death, Lockups, Restarts and sometimes Data Loss by corrupting data as a result of crashes.

Motherboards these days are generally stable, regardless of what it is. You should however be aware of the brand and model of the motherboard supplied as it may affect future upgradability.

Lesson Learnt - If the computer you're interested in buying on eBay does not specify the brand and model of the components used, either ask for more information or walk away from the product!

2) False Advertising - Do not be a sucker to false advertising.

A major culprit of this is with CPU's featuring more than one core. Many sellers try and put across the notion that the power you get from a CPU in terms of it's frequency is multiplied by the number of cores that the CPU has.

e.g. - An AMD Phenom II X4 940 Black Edition 3.0GHz Processor is 12.0GHz!


There are many things wrong with this kind of advertising as it's down right misleading. If you're led to believe that having four cores will result in the equivalent of a 4x speedup you're going to be disappointed. But why is this the case?

1) Not all software fully utilises multiple cores. Infact, a large number of applications still use two or even just ONE core.

Suppose we have two systems, each running a game that can utilise TWO cores. System #1 has a Core 2 Quad Q9650 3.00GHz processor and System #2 has a Core 2 Duo E8400 3.00GHz processor. As in both circumstances only two cores can be utilised. The other two cores of the Quad are effectively idling and not doing anything of use, meaning that both system's performance in this circumstance will be the SAME.

2) Due to inefficiencies at BOTH HARDWARE and SOFTWARE level, a 2x Speedup on a Dual Core or a 4x Speedup on a Quad Core isn't possible. It may come pretty close to it but even so, it's enough of a difference to consider multiplying frequencies a false claim

3) This is pretty fundamental. You can't multiply the frequency of the processor by the number of cores because quite simply it doesn't work like that. A Frequency is a rate. A rate at which one operation occurs. Saying that two entities doing one operation each is not the same as a single entity doing both operations at the same time. It's like saying that two Vauxhall Corsa cars driving next to each other at 70mph is the same as a single Bugatti Veyron speeding away at 140mph!

So that's basically it. I'm not saying that you should avoid sellers that are trying to claim this as it could well be out of pure ignorance than deliberate misleading, but you should be aware of what I've mentioned to avoid disappointment.

Another false claim is the TYPE of computer that is being sold. Typically this is often computers labelled as GAMING PC's when infact they're not. By definition, a gaming machine should be able to play modern hits WELL. That means in high detail and with fluid framerates!

Lesson Learnt - Carry out your own research on all the components that have gone into the machine to make sure that you're getting exactly what you want.

3) Missing Software and Quality Assurance

Many computers sold on eBay ship WITHOUT operating systems. In order for your purchase to be of any use you will require to purchase an operating system such as Windows XP or Windows Vista. You will need to factor this into the overall cost of the machine as Windows XP will cost at least £40 and Windows Vista will cost at least £80. Further, you will also need to install all of the drivers for the hardware in the machine to function properly. Sometimes it is more convenient to opt for a seller that is willing to at least install everything for you at an extra charge.

The final thing to mention about this is more serious. The computer is an overglorified jigsaw puzzle. Within this jigsaw puzzle may lie a faulty part. Much of the time, the seller needs to run tests on the machine to ENSURE that all components are in working order. This requires an operating system as many of the tools required to test the components run on Windows OS' for example.

I recommend emailing the seller to confirm that the system has been stress tested to ensure reliability. What the seller does to test it is at their own discretion but ideally, the CPU, RAM and Graphics Card should all be independantly tested and also tested together under full load. It's not necessary for the seller to have to do this but you should expect confirmation that some form of Quality Assurance testing will be done before the system is shipped!

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