PC components are cheap because they're all based on standard designs which are interchangeable. Buying a barebones system means you can build yourself a machine that's a little out of the ordinary.

1. Deciding what you want.

What is a barebones system?

* It's a PC that consists of a case, motherboard and power supply. You get to choose the CPU, memory, hard drive, keyboard and display that fit your budget. Remember that you'll need a copy of Windows as well though.

* Most barebones systems are non-standard designs. Shuttle, for example, uses a motherboard that won't fit into a normal ATX case, and a bespoke power supply too. Make sure that the components you want – such as a graphics card or multiple hard drives – will fit into the overall power envelope offered by a barebones system before you buy.

Why would I want a barebones system?

* Nearly all barebones systems are smaller, cooler and more power efficient than their off-the-shelf brethren.

* Many excellent designs for media centre PCs are sold as barebones systems.

* These are usually called Small Form Factor (SFF) PCs.

* You can save a lot of money by opting for a barebones system.

I want a barebones system. What else will I need?

* Your system comes with a case, motherboard and PSU.

* You'll also need a CPU, hard drive, optical drive and memory. You may also want to add-in a graphics card or sound card, although most have low end ones integrated.

* You won't need any networking kit, USB cards or heatsinks. All the basic components will be built into the motherboard, and a custom CPU heatsink will also be.

Are barebones systems as powerful as regular PCs?

* Many SFFs – such as those from Shuttle and Aopen – use standard PC parts for everything other than the motherboard and PSU.

* They tend to run hotter than normal PCs – due to the small space in which components are confined – so aren't ideal for performance machines.

* Some barebones systems use mini-ITX motherboards and chips. These won't be as powerful or upgradable as a normal PC, but they will be even smaller than other SFFs.

What are the downsides?

* You may not be able to use high-end components due to power and heat restrictions.

* You'll have to fit all the components yourself.

* The overall cost may be higher than building a PC from standard equipment, if you're opting for an SFF.

* Some barebones systems are very noisy, as the small fans have to work hard to dissipate heat.

I don't want to build my PC. Will someone sell me one of these SFF systems ready made?

* Yes they will. Shuttle has a UK shop, and system builders such as Scan have integrated barebones systems into their regular product line.

What other barebones systems are available?

* Some websites are now selling barebones laptops as well as barebones desktops. These include the chassis, motherboard and screen; all other components are your choice.

2. Seeing what's available

Most system builders and online component stores now sell barebones systems, and prices are coming down all the time – they currently start at around £150. If you want a PC that's a little different from the mainstream and will fit into your home or office discretely, build a system from a barebones chassis might well be for you.

Here are the top barebones systems that TechRadar currently recommends:

FIC Spectra HTPC

Shuttle XPC

AOpen Mini PC

3. Our advice

Barebones systems are simple to put together and building one will give you a great sense of achievement, but that's only the start. Small enough to carry around with you if you wish, they're a great alternative to a laptop for mobile presenting. They're usually better designed than desktop cases, and make perfect media servers, while also running at lower power for constant downloading. Shuttle are still the best in the market, but Aopen's Mac Mini aping chassis are winning the battle for living room acceptability.

Finally, Hoojum's cases are almost bulletproof, they're so robustly designed. And some models now accept parts from Shuttle PCs: which means that the barebones PC is now upgradeable.