All-in-one PCs offer a convenient halfway house between a laptop and a desktop PC, offering great space-saving advantages but also offering a big-screen which can also be used as an entertainment centre – perhaps to replace your TV. Here's our all-in-one PC buying advice.

Below we've reviewed six very different all-in-ones with unique strengths and weaknesses, and you can check out our most recent all-in-one PCs group test, but first let's look at some general All-in-one PC buying advice.

All-in-one PCs buying advice

Choosing an all-in-one PC is about more than performance. Often used as family multimedia entertainment system, it can be treated much like a TV and will therefore be subject to the same aesthetic considerations as any other entertainment system you install in the home.

Many Windows AIO PCs incorporate Blu-ray players and TV tuners and come with remote controls. They often incorporate a touchscreen interface, with the idea of freeing you entirely from the mouse and keyboard until they're needed.

Windows 7 incorporates multi-touch control as standard, so you can try navigating your way around the operating system if you need to. However, don't expect to have much fun jabbing away at the standard Windows 7 interface. Windows Media Center, on the other hand, is more usable by finger or remote control than a keyboard and mouse.

All-in-on PC Most all-in-one vendors also add their own software to help keep you away from the ill-suited Windows desktop, making the interface more touch-friendly.

Windows 8 is able to make much greater use of touch input, but places more stringent requirements on the touch interface if it is to be certified. Most touchscreen PCs will work, but because many gestures involve swiping the finger in from off the side of the screen, raised bezels get in the way. It's also a requirement that at least five touch points are recognised, so those systems which support only two points (of which there are many) will struggle.

Of the systems reviewed below, only the Lenovo IdeaCentre A720 meets both of these requirements, although no Windows 8 compatibility is claimed for even this system. With few good standalone touchscreens available, a suitably-specced all-in-one PC may be the best way to get a touchscreen PC now which will deliver in Windows 8.

As with any display or TV, you should also consider the screen size you need. Larger screens are more expensive but provide a better viewing experience for multiple viewers. In many cases, all-in-one PCs support HDMI inputs so you can plug in a set-top box or games console. You also get HDMI outputs to set up dual-screens to boost work productivity or connect a projector.

All the systems in our group include full-HD (1080p) or better screens. Look out for a Blu-ray drive to take advantage of these high-res panels when watching films.

With all their components crammed into a thin housing, all-in-one systems must make compromises between performance and noisy cooling. To cut down on heat and power consumption, some machines use low-power processors such as the Intel Core i5-3450S or mobile processors like the Intel Core i7-3610QM. These PCs are generally much quieter to use and these latest third-generation Intel processors pack more than enough power for the vast majority of users.

All-in-on PC Watch out for systems using standard desktop chips like the Core i5-3570K. Powerful as they are, the level of cooling required can often result in an unpleasantly noisy PC.

Due to space and cooling constraints, all-in-one systems rarely offer strong gaming performance. With modern Ivy Bridge processors, there's enough graphics power built-in for multimedia and even low-level gaming. In many cases there's now no need to pay for discrete graphics.

However, most of the systems here incorporate a mobile nVidia chip to give graphics a performance boost. PC Specialist's system uses a desktop graphics card, which gives considerably faster gaming frame rates but is particularly noisy and for keen gamers only.

All-in-one PCs aren't all about fun and games. If you're a designer working from home who needs workstation-level performance, reliability and service, take a look at HP's unique Z1 workstation.

All-in-one PC reviews

All-in-one PC Here are reviews of a range of all-in-one PCs, with screen sizes from 21.5in to 27in, and prices starting from £799.

All-in-one PCs: The iMac challenge

Apple iMac The resurgent popularity in all-in-one computers can be traced to Apple's long-running iMac. It's evolved from the classic Bondi Blue model of 1998 to the flatscreen form that's now being emulated by other PC vendors, and comes in either 21.5in or 27in screen sizes.

Apple's iconic all-in-one still offers the finest balance of high-grade IPS screens like that in the HP Z1 workstation, along with peerless build quality and cool, quiet operation. Prices start at £999 for the Apple iMac 21.5in model we tested late last year, or £1399 for the entry-level 27in Apple iMac 27in (Mid-2011) 2.7GHz Core i5 we tested in March.

All iMacs sport quad-core processors and discrete graphics, although the range has yet to be upgraded with Ivy Bridge processors and USB 3.0 ports – a new range is expected imminently.

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