Battle of the pint-size PCs: Cotton Candy, MK802 II, and Raspberry Pi face off

Today’s smartphones are pretty good computers, but we’ve tried out three computational powerhouses that make the slimmest phone look like ENIAC. (The world’s first electronic computer, unveiled in 1946, weighed 27 tons and consumed 1800 square feet of floor space.) The Cotton Candy, the MK802 II, and the Raspberry Pi are amazingly tiny, incredibly inexpensive, and eminently customizable. They make terrific platforms for hobbyists fond of experimentation, and they’re ideal for students interested in learning how to program, but they can also serve as ordinary productivity machines.

These miniature marvels eschew the power-hungry x86 processors found in desktop and laptop PCs in favor of mobile CPUs and GPUs, but each relies on an external monitor or HDTV—connected via HDMI—to display its user interface and other video output. In fact, the Cotton Candy and the MK802 II are the same shape and size as a USB memory stick, and plug directly into a TV. Thanks to that skimpy hardware, these computers can operate on just the trickle of energy provided by the display they’re connected to. Alternatively, you can plug in the same type of USB AC power adapter that modern smartphones and tablets use.

Much of the appeal of these pint-size PCs lies in their software versatility. Each device can boot from a MicroSD card containing an operating system disc image (typically some flavor of Android or a Linux distro tailored to its hardware set). If your tinkering utterly demolishes the stability of the OS, you can just overwrite the memory card with a new image and start over.

After comprehensive testing, I found that each of these micro PCs has its upside and downside, but all three devices shine in distinctly different scenarios.

What you’ll need to provide

Although each of these micro PCs is incredibly inexpensive, you’ll need to spend a little more cash on peripherals and accessories to render them completely functional. You'll absolutely need a USB mouse and keyboard, for instance, although you could borrow the input devices from another computer you already own. Raspberry Pi buyers will want to pick up an enclosure for protection (the device arrives as a populated circuit board sans case).

Depending on the port selection on your device, you might need to grab a USB hub to connect your peripherals. Be aware, however, that not every AC adapter will provide enough juice for the computer and a passive hub. (In my situation, the charger for my Kindle Fire did, but my smartphone charger did not.) You might also need to provide some of your own cables: The MK802 II and Cotton Candy come bundled with enough cables for the typical usage scenario, for instance, but nothing is included with the Raspberry Pi.

If your chosen device lacks on-board flash storage, you'll also want to buy a MicroSD card on which to burn your operating system disc image. Suppliers who sell micro PCs typically also stock cards with various OSs preburned on them; but if you want to do it yourself, a tutorial at eLinux.org will walk you through the process.

How we tested

I had difficulty finding benchmark software that behaved consistently across all three platforms. In consultation with the PCWorld Labs crew, I initially planned to use three browser-based benchmarks—Sunspider, Peacekeeper, and WebVizBench—but the fact that each device used a different browser made an apples-to-apples-to-apples comparison impossible. Not only that, but having each computer connect to the Internet via Wi-Fi created yet another uncontrollable variable. In the end, I was skeptical enough of the results these tools produced in this particular scenario that I elected not to disclose the results; I just didn’t think they proved anything. Although this decision renders my opinion more subjective than usual, I’m confident it was the right way to go.

Cotton Candy 

The tiny-PC market is evolving so rapidly that products are in danger of becoming obsolete before they hit virtual retail shelves. FXI Technologies announced its Cotton Candy micro PC just over one year ago, but the company has had to put the device through numerous design changes to keep it competitive.

The result is a product that could appeal to both consumers and business users—whenever it ships as a finished product, that is. As of this writing, the Cotton Candy’s firmware and operating system are still in beta, and the manufacturer states that the device in its current state is intended only for developer use. Developer units are available for purchase direct from the manufacturer for $199. For this evaluation, FXI sent us a unit with two MicroSD cards containing beta builds of Android Ice Cream Sandwich and Ubuntu Linux, respectively. The manufacturer is in the process of certifying the Cotton Candy with Google, but currently you cannot load apps from the Google Play Store unless you load a user-created Android OS image that's downloadable from the FXI user forums.

For more, read our full review.

MK802 II

The MK802 II is an intriguing Android-on-a-stick computer made by the Chinese manufacturer Rikomagic. It resembles a USB thumb drive. Inside the cheap-feeling plastic case, you’ll find a pedestrian, single-core Allwinner A10 CPU (based on ARM's Cortex-A8 architecture); 1GB of RAM; and 4GB of flash storage (half of which is consumed by the rooted Android 4.0.4 operating system, aka Ice Cream Sandwich). The unit's Mali 400 GPU is theoretically capable of playing 1080p video, although the stick seems stuck at 720p for other applications.

This tiny computer is available from a few small online retailers, including W2Comp.com, which is where we acquired ours. The firm is based in Hong Kong, but it sells the MK802 II for a very competitive $55—including free shipping to the continental United States. It took a while to reach us after crossing the ocean and clearing U.S. Customs.

For more, read our complete review.

Raspberry Pi

Very small computers—based mostly on the 6.7-by-6.7-inch Mini-ITX motherboard—have been around for a while, but the launch of the 3.4-by-2.2-inch Raspberry Pi generated a frenzy of public interest. The model A (256MB of memory, one USB port, no LAN port) sells for $25, while the model B reviewed here goes for just $35. The model B has 512MB of RAM, two USB ports, and 10/100MB ethernet.

The design intent behind the Raspberry Pi was to rekindle interest in computing as a children’s hobby, with modern PCs having become too expensive for parents to allow their kids to experiment with them. But the machine has become a hit with grown-ups, too, and the tiny computer has spawned dozens of competitors. The nonprofit Raspberry Pi Foundation recently announced plans to build 30,000 units each month.

For more, read our entire review.