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Zotac's Zbox HD-ID11 barebones nettop

Roll your own second-gen Ion HTPC

I can't help but be amused by the fact that Intel's Atom CPU has become quite possibly the most important CPU of the past couple of years. The Atom has certainly proven to be popular, but in truth, its success has been largely accidental. The chip was designed for mobile Internet devices (MIDs) with an eye toward eventual migration down to smart phones. Those MIDs never materialized in great numbers, though, and Intel only just recently introduced an Atom Z600 series that's appropriate for future iPhone alternatives.

Despite failing to make an impact in the markets it originally targeted, the Atom unwittingly fueled a netbook revolution that brought affordable ultraportable Windows computing to a broad audience of PC enthusiasts and mainstream users alike. Then along came nettops, which followed the same basic premise as their mobile predecessors: small footprints, low power consumption, budget prices, and just enough horsepower for the basics. Although not as revolutionary as their ultraportable cousins, the sheer number of nettops on the market suggests considerable interest in that class of system.

Generally speaking, I haven't been a fan of nettops. I'm not prejudiced against the Atom¬ójust its integrated graphics component, which even in the latest Pine Trail revision lacks decode acceleration for HD and Flash video and is all but useless for games. That's not much of a loss when you're dealing with a netbook with fewer pixels than 720p video requires. The Atom at least provides exceptional battery life in return for tolerating its lack of muscle. However, nettops spend their lives tethered to electrical sockets and are often plugged into high-def displays, especially in the living room. For those environments, you really need something that behaves more like a fully functional PC.

In my view, the Atom is only a competent graphics component away from fueling the popularization of home-theater PCs. One need look no further than Zotac's Zbox HD-ID11 to see why. This tiny little nettop houses Intel's latest dual-core Atom, an Ion redux from Nvidia, 802.11n Wi-Fi, and all the connectivity one might need in the living room. Enthusiasts will appreciate the fact that the Zbox is a barebones affair that lets the user add his own memory, hard drive, and operating system. Oh, and it costs only $220. We had to check one out for ourselves.

Introducing the next-generation Ion
The Zbox is our first look at the second coming of Nvidia's Ion. Nvidia originally brought Ion graphics to the Atom platform with a rebadged GeForce 9400 chipset that had spent most of its life catering to Core 2 processors. Despite their differences, the Core 2 and original Atom use the same front-side bus, making it easy to share integrated graphics chipsets between them. All of that changed with Intel's Pine Trail Atom refresh, which moved the traditional north-bridge chipset components, including the front-side bus, entirely onto the CPU die. The latest Atoms have only a DMI interconnect to interface with a south bridge chip or I/O hub.

Nvidia doesn't have a license for Intel's DMI interconnect, so it had to dig through the parts bin once more to find a suitable Atom sidekick. It emerged with a GT218 graphics chip that's pulled duty in low-end GeForce 210 and 310 graphics products on the desktop and in notebooks. The GT218 can now add "next-generation Ion graphics processor" to its resume.

In truth, the GT218 is probably all the graphics horsepower one needs in an Atom-based system. This GPU has a DirectX 10.1-compliant core running at 535MHz with 16 CUDA cores shader processors clocked at 1.2GHz. (A version of the Ion GPU tailored for 10" netbooks is also available with just eight SPs). The original Ion shared system memory with the CPU, but its successor is paired with either 256 or 512MB of dedicated video RAM that's linked to the GPU by a 64-bit memory interface. Zotac takes full advantage in the Zbox, providing the Ion with 512MB of GDDR3 clocked at 790MHz.

The GT218's PureVideo HD decode block is easily the GPU's most important element, at least for Ion. This dedicated logic provides full HD decode acceleration, promising smooth video playback up to 1080p resolution with MPEG2, H.264, and VC-1 content, including Blu-ray movies. Dual-stream decode acceleration is supported, as well. When paired with Flash 10.1, PureVideo HD can also accelerate Flash video playback.

Intel has severely limited the display controller in Pine Trail Atoms, restricting digital output to an LVDS interface with a maximum resolution of 1366x768. Fortunately, the Ion GPU kicks in an HDMI output that'll have no problem powering a high-def display. Uncompressed eight-channel LPCM audio can also be passed over HDMI to a compatible receiver or speakers.

A block diagram of the new Ion. Source: Nvidia

Although the latest Ion technically supports Nvidia's Optimus auto-switching technology, the feature doesn't really mesh well with nettops. First, Optimus requires that all output be routed through the display controller in the Intel integrated graphics processor. You know, the one that only does digital output up to 1366x768 and doesn't support HDMI. That's not gonna fly for nettops or anything that taps the Ion's wealth of display outputs. Optimus switching is better suited for netbooks, where its battery-saving potential is most valuable, anyway. Besides, Optimus uses PCI Express to pass the contents of its frame buffer to the Intel display controller, presenting a further challenge because the Ion GPU hooks into the Pine Trail platform using a single first-generation PCI Express lane.

A gen-one PCIe link only provides 250MB/s of bandwidth in each direction, which adds up to less total bandwidth than an old-school AGP 2X interface from back when flannel was cool. Such a narrow pipe requires specific optimization, and Nvidia says that its Ion drivers store frequently accessed data in video memory to conserve interface bandwidth.

The Ion GPU is stuck with such a low-rent interface because that's the best one available in Pine Trail's NM10 Express Platform Controller Hub (PCH). There are actually four PCIe 1.1 lanes sprouting off the NM10, but two of them are monopolized by the Zbox's Gigabit Ethernet and 802.11n Wi-Fi controllers. The NM10 Express also feeds the Zbox's USB and Serial ATA ports, along with a pedestrian Realtek audio codec.

The DMI interconnect then provides a 2GB/s link between the Zbox's NM10 Express PCH and its Atom D510 CPU.

This dual-core Atom runs at 1.66GHz and can execute four threads simultaneously thanks to the wonders of Hyper-Threading. Its on-die memory controller has only a single channel of DDR2, but that'll probably be sufficient for a system of this caliber, especially since the Ion GPU has its own dedicated RAM. You can read more about Intel's Pine Trail Atom platform in our review of Asus' Eee PC 1005PE netbook.