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.