The all-in-one PC is enjoying more exposure after the appearance of Windows 8. In the Windows world, it's about the only way to get a large-format PC with a decent touchscreen – a feature that greatly enhances the Windows 8 experience.
See also: What's the best all-in-one PC?
An all-in-one also offers great space-saving advantages and has a much bigger screen than you'd find on a laptop. Some also double as entertainment centres capable of playing films, music and, to some extent, games. Lenovo's Horizon in particular is aimed at family fun, with educational and unique touch-enabled gameplay brought to the fore.
In choosing an all-in-one PC you should take into account much more than its performance. Sometimes used as family multimedia systems, all-in-ones will be subject to the same aesthetic considerations as any other home-entertainment system. The same goes for their reliability and freedom from technical maintenance.
Many Windows all-in-one PCs incorporate Blu-ray Disc drives and Freeview TV tuners, and are supplied with a remote to control them from across the room like a telly. Most of the Windows PCs reviewed here incorporate a touchscreen interface, freeing you from the keyboard and mouse in some activities.
Other all-in-ones, notably Apple's iMac reviewed here, don't offer touch control – favouring traditional input methods instead. Although Apple's introduction of multi-gesture control to it mice and desktop trackpads is anything but traditional.
If you are considering making use of touchscreen input, look for a PC which tilts a long way towards the horizontal, to enable comfortable prolonged use. Holding your arms out to control a PC will otherwise prove wearing.
The move to Windows 8 has increased the demands made on touch screens. Microsoft requests its hardware makers to create flush, frameless screens with 10 touch points for a satisfactory experience. All of the touch screens reviewed here meet this requirement.
It's wise to start by considering the screen size you need. Some all-in-one PCs have an HDMI input for plugging in a set-top box or games console, for which you might want a large screen. HDMI outputs let you add another screen, or a projector. You might also want a Blu-ray drive to get the best movie experience.
With all their components crammed into a thin housing, an all-in-one system must compromise between performance and noisy cooling. Some use mobile or low-power processors such as the Intel Core i7-3537U or i7-3770S to reduce heat and power consumption – note the U and S suffices that denote low-power chips. These PCs are generally quieter in use, while third and fourth-generation Intel processors pack more than enough power for the vast majority of users.
Due to space and cooling constraints, all-in-one systems rarely offer strong gaming performance. Haswell and Ivy Bridge processors provide enough graphics power built-in for HD video playback and low-level gaming, so for many people there's now no need to pay for discrete graphics. However, some of the systems here incorporate a laptop-tuned nVidia processor to boost the graphics. If you really want to enjoy games to the full, the 27in iMac offers by far the quickest graphics of the group – at a price.
Most all-in-ones have flexible configuration options and can be tweaked to fit your requirements and budget. If a PC is too expensive for you, consider cutting back on some of the options. Faster versions of the less-expensive systems are often available by selecting a faster processor at the time of purchase.
However, we wouldn't advise trying to save money in Windows 8 by opting for processors slower than the ones reviewed here: the new OS needs a certain peformance of chip to process its touch control, and may start to look less smooth.
All-in-one PCs: Conclusion
For those with limited funds, the cheap Medion Akoya P2002 is an obvious choice. Its performance is adequate and its build quality is higher than you might expect for the £449 price, which is well under half the price of any other PC in this group test. In fact you could buy two for the price of the next least expensive and have nearly £250 left over. It offers a smaller screen than most and comes without touch input or Blu-ray, but does include a Freeview TV tuner. It therefore earns a recommended award for sheer value for money.
All-in-ones are often bought as family entertainment centres, but if you want to get the whole family involved at once, you may like to consider the Lenovo Horizon table PC. It folds flat to allow multiple simultaneous players to gather around it and comes packed with educational and entertainment software.
For any serious work, you can't go wrong with the 27in Apple iMac. With build quality and design second to none, this will look good in any home or office environment. It'll also deliver excellent performance and, perhaps surprisingly, the best gaming graphics of the group. It's designed to run Mac OS X, but you can use Boot Camp to easily install Windows within a partition of the drive should you have to, or run Windows virtualised without even rebooting – perhaps to gain access to some Windows-only games. Despite the lack of touch input, the fantastic 2560 x 1440 IPS display places it near the top of the list for any serious artist or photographer and is an obvious choice for a recommended award.
Dell's XPS 2720 may be the most expensive all-in-one on test, but it is truly excellent throughout. The 27in display trumps even the iMac by supporting the full Adobe RGB colour space and adding touch support to its 2560 x 1440 pixels. Its quad-core Haswell processor, combined with a solid-state cache for the main disk helped it achieve almost 50% more performance points than the iMac when running PCMark 7 for Windows. It'll also have a decent stab at playing games, although here the roles are reversed, with the iMac delivering around double the speed. A full selection of features, including Blu-ray, Thunderbolt and six USB 3.0 ports along with Dell's excellent support and in-home service earns it out Best Buy award.
All-in-one PCs: How we test
Core system performance is measured using PCMark 7 in Windows, an industry-recognised test suite that uses 25 different workloads to measure areas such as storage, computation, image and video manipulation, web browsing and gaming.
As well as the overall PCMark 7 result, typically a point score between 3000 and 7000 with current hardware, we have also published results garnered from some of the suite's sub-routines. These are designed to gauge performance in, for example, creativity and entertainment scenarios.
Another test highlights the difference between storage technologies. This is an area that impacts perceived speed more than ever, now that even the slowest modern CPUs are more than fast enough for everyday PC duties. PCMark also measures multimedia-transcoding performance, which can take advantage of GPU acceleration.
Most all-in-ones aren't designed for gaming, although some do offer powerful discrete graphics chips. We've run a single game, Alien vs Predator, at 1280 x 720 and full-HD resolutions with High Quality settings enabled. This is enough to reveal differences in gaming performance. Systems with integrated graphics seldom perform to a satisfactory level in these tests, but Windows programs and casual games will usually run sufficiently well.
We allow overclocking of the processor only in dedicated gaming computers. All other components are run at their stock speeds, with the exception of factory-overclocked graphics cards, which are designed and sold at boosted speeds.
We measure the power consumption of each PC while it's idling at the desktop and has settled down after booting up. We then set the display brightness as close as possible to our standard brightness setting of 120cd/m2. We then turn the brightness up to maximum and measure again. Finally we measure again while pushing each PC to the limit by simultaneously running Prime95 (with the maximum number of available threads) and the Furmark burn-in test. This pushes both processor and graphics utilisation to the absolute limit. Real-world power consumption will fall somewhere between these two measurements, depending on use.
We also record processor temperatures while stressing the systems, keeping an eye out for any problems with overheating and listening to the noise levels produced as the cooling systems come into full effect.
We use a Datacolor Spyder4 calibrator to measure colour gamut and accuracy, contrast and uniformity across the surface of the screen. We also take into account the viewing angles afforded by the display technology used by each panel. Higher-resolution displays can score extra points simply for having more pixels and being able to deliver sharper graphics.
It's not all about speed. We also pay close attention to the physical characteristics of each all-in-one PC, its noise output and build quality, and take note of important features such as the quality of components.
Warranty and support
Differences in warranty terms can affect our verdict. Obviously, longer warranties are better, but we also look at the terms and conditions – specifically, whether faulty systems must be returned to the vendor at your own cost, and if both parts and labour are included. In-home support is particularly welcome.