Windows-based all-in-one PCs once earned little respect. While most of today's AIOs still lack the graphics horsepower for hard-core gaming (we'll show you one exception), the best models are far removed from the 98-pound weaklings of yore.

Many AIOs use laptop parts, which minimize heat, power consumption, and the need for noisy cooling fans. If you crave more performance, pick a model that uses desktop components (the ones we've tested are still relatively quiet). Either way, everything—the CPU, memory, storage, and optical drive—is housed in the same unit as the display, so the computer's footprint equals that of a monitor. And since most all-in-ones ship with a Wi-Fi adapter as well as a wireless mouse and keyboard, the only cable they require is a power cord.

All-in-one specifications are a blend of what you'll find in conventional desktop systems and laptop PCs. The thinnest and most compact systems are almost completely built around the same power-efficient technology as laptops.

Here's our checklist of specs to look for when you go shopping for your all-in-one, followed by some tips and recommendations:
The specs explained
Display: Unlike with traditional desktop PCs, with an all-in-one computer, what you see is what you get—for the life of the PC. With few exceptions, you'll never be able to upgrade without chucking the entire machine, so choose accordingly. In addition to multitouch capabilities (to support Windows , you should consider three other key factors: display technology, display resolution, and display size.

LCD panels that employ IPS (in-plane switching) or PLS (plane-line switching) technology are vastly superior to those based on TN (twisted nematic) technology. IPS and PLS displays are more expensive, and you might find them only in larger all-in-ones, but they are worth every cent.

The all-in-one you buy should deliver graphics resolution of at least 1920 by 1080 pixels. Movies, digital photos, websites, and productivity apps will look great at this resolution on a 23- or 24-inch display. Move up to a 27-inch model, however, and you'll be able to make out the individual pixels because they'll be spaced farther apart to fill the larger area. A few high-end AIO models, such as Dell's XPS One, provide higher resolution—2560 by 1440 pixels—on their 27-inch displays.

CPU: Desktop or mobile? Choose an all-in-one with a desktop processor if you intend to perform in-depth photo editing, manipulate complex spreadsheets, or engage in other computing-intensive tasks. If your work is less demanding, an AIO built on a mobile CPU will be thinner and quieter, and will consume less power. Faster clock speeds buy incremental performance within a particular class, but your desktop-versus-mobile decision affects performance the most.

Memory: Look for systems with at least 6GB to 8GB of memory. Most all-in-ones offer relatively straightforward memory expansion, so you can add more if you need it; but you might discover that a limited number of memory slots will force you to replace existing memory modules with higher-capacity ones, rather than add to existing DRAM.

Graphics: Buy an AIO with discrete graphics if you plan on any serious gaming; models with integrated graphics hardware won’t be up to the task. Note, however, that the limited airflow in an AIO design typically restricts the manufacturer to using a mobile graphics processing unit. Such GPUs can run 3D games, but you will need to dial down the resolution and detail levels to achieve acceptable frame rates.

To date, we know of only one AIO PC that uses all desktop components, including a top-of-the-line Nvidia GeForce GT 680 GPU: the Maingear Alpha. We expect to get one of these machines into the PCWorld Labs for a hands-on-review soon.

Storage: Most AIOs use mobile hard drives, which trade capacity and performance for smaller size and cooler operating temperatures than desktop PCs. You’ll want at least 1TB of storage. We’ve seen only a few AIO PCs outfitted with solid-state drives, but some higher-end models use small SSDs as a persistent cache for higher-capacity mechanical drives.

Optical drives: Entry-level AIOs come with DVD burners/players. Upscale models should come with a least a Blu-ray player (if not a Blu-ray burner). If you're buying a custom configuration and don't think you'll ever watch Blu-ray movies on your computer, you can save a few dollars by including a less-expensive DVD burner in your machine.

Lenovo AIOPhoto courtesy of LenovoThe display on Lenovo's IdeaCentre A720 can fold completely flat.
Connectivity: Only the most basic AIO won’t have an integrated Wi-Fi adapter. If the machine you choose lacks one, you can add it by plugging in an aftermarket USB adapter (choose either 802.11n or—for a future-proof network—an 802.11ac model). Bluetooth support is convenient for connecting Bluetooth printers, tablets, and smartphones.

I/O ports: The all-in-one you select should have at least two USB 3.0 ports, but the more, the better (either USB 2.0 or USB 3.0). An eSATA port will enable you to attach a very fast, high-capacity, external mechanical hard drive. A flash memory card reader (SD, Compact Flash, Memory Stick, and the like) is another welcome feature, since it can make quick work of copying files from your digital camera or camcorder.

HDMI: An HDMI input lets you connect a gaming console, a cable or satellite set-top box, a camcorder, or another digital video source to your all-in-one to take advantage of the computer’s display. Models that allow you to use the display without turning on the computer will consume less power. HDMI-out is a less common feature on AIOs, but you could use it to drive a second display.

TV tuner: An onboard TV tuner lets you watch over-the-air broadcasts on the AIO’s display. If you subscribe to cable or satellite TV, however, you’ll be much happier plugging a set-top box into the machine’s HDMI input.
Buying tips
Avoid buying last year’s models: Although you can score a big discount on an older model, buying an outdated AIO is problematic. It’s unlikely to come with Windows 8 installed, and it probably won't have the type of multitouch display you’ll want to use with Windows 8 should decide to update your OS later.

Remember that you can’t upgrade: Upgrading a desktop PC is easy, particularly if you want to improve its graphics, storage, display, or optical drive. With few exceptions (such as the aforementioned Maingear Alpha), upgrading an all-in-one is at least as difficult as upgrading a laptop. The key is to buy as much computer as you can afford, so that you won’t outgrow it too quickly.

Products we like
If you don’t plan to upgrade to Windows 8, you won’t care that Dell’s XPS One lacks a multitouch display. The 27-inch, 2560-by-1440-pixel PLS display is so beautiful, you might not even care if you do upgrade. A beast lurks beneath that beauty, too, in the form of Intel’s 3.1GHz Core i7-3770S desktop CPU and Nvidia’s GeForce GT 640M mobile GPU. You also get a Blu-ray player, a 2TB desktop hard drive plus an SSD cache, and HDMI-in and -out. Dell is now shipping a version of this machine with Windows 8, but with the same nontouch display

Source: http://www.pcworld.com/article/2013591/how-to-choose-just-the-right-all-in-one-computer-for-you.html

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