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Nvidia's Ion platform

A GeForce for Atom
— 8:00 AM on February 3, 2009

Although Intel's wildly popular Atom processor was originally conceived for mobile Internet devices with an eye toward eventually trickling into smartphones, it quickly caught on with netbooks and has since carved out a sizable chunk of the mobile landscape. The concept of cheap, fast-enough computing soon migrated from portables to the desktop, where it spawned a new class of delightfully small nettop systems. With Atom now available with two physical cores and an economic downturn causing many to tighten their budgets, the nettop looks to have a promising future, especially in cheap, media-centric PCs.

Except for one problem: while the Atom has just enough horsepower to deal with common, everyday tasks, the platform it's available on is an outdated throwback. Intel pairs Atom with its 945G-series chipsets, which first saw life way back in 2005. The 945 series isn't horribly lacking in the peripherals department, and its performance is acceptable given the Atom's modest aspirations on that front. But the chipset's Graphics Media Accelerator 950 is several generations behind the curve. The GMA 950's game compatibility is flaky, and its performance dismal. Even worse, it's unable to accelerate high-definition video playback. That might not be the sort of thing you need in a netbook with a limited 1024x600 display resolution, but a desktop or home theater PC plugged into a real monitor or high-definition TV is an entirely different story.

The Atom's antiquated chipset is clearly limiting the processor's appeal for some devices, but help has arrived from Nvidia in the form of the Ion reference design. More a new application than fresh silicon, the Ion platform pairs the Atom with the very same GeForce 9400 integrated graphics chipset you'll find on motherboards designed for Core 2 processors—except instead of arriving on a Micro ATX or Mini-ITX form factor, the Ion reference platform is about the size of a deck of cards.

On its specifications alone, the Ion platform looks to be capable of significantly broadening the Atom's horizons. But there are limitations to what this graphics and core logic package can do given the processor's inherent limitations. Read on to see how Nvidia's first Ion design pans out in the real world.

Atom gets a brand new ride
If you aren't already familiar with Nvidia's GeForce 9400 chipset, I suggest looking over our detailed review of the GeForce 9300. The 9300 was launched last fall on motherboards with LGA775 sockets, and it's essentially the same chip that you'll find in the Ion platform. In fact, the GeForce 9400 really is the platform. To understand the Ion reference design, then, we must first explore its GeForce.

As far as motherboard GPUs go, the GeForce 9400 is Nvidia's newest and its best. On the desktop, where it runs with Core 2 processors, the 9400 easily trounces Intel's latest G45 Express integrated graphics chipset. With an Atom onboard, however, the GeForce only has to compete with the lowly 945G chipset series—designs whose roots are four years old. In the world of over-used tech site car metaphors, that's like lining up the latest BMW 1-series against a four-year-old Toyota Echo. Not that we'd stoop to such lazy and repetitive clichés.

As its name implies, the GeForce's integrated graphics core really is the star of the chipset. This is an honest-to-goodness GeForce 9-series GPU, complete with full support for DirectX 10, Shader Model 4.0, and of course, the slow trickle of CUDA-aware applications that leverage GPU power for general-purpose processing. The GeForce 9400 has 16 shader CUDA processors running at 1.1GHz, and they're paired with four ROPs and a 450MHz graphics core. Those clock speeds are comparable to those of the GeForce 9300 for LGA775 processors, which also runs its core at 450MHz but clocks its shaders at 1.2GHz. Don't ask me why a lower shader clock earns the Ion platform's GeForce an extra hundred points.

On the desktop, the GeForce 9300 doesn't have the grunt to match the performance of even a $50 discrete graphics card, so it's not the best gaming value around. But Intel doesn't let its partners build Atom platforms with PCI Express x16 slots, so discrete graphics upgrades are out of the question. That pits the GeForce 9400 solely against the antiquated GMA 950.

And, as we've noted, the GMA 950 cannot accelerate high-definition video decoding. The Atom doesn't have the horsepower to handle HD decoding on its own, not even with a second core. However, the GeForce 9400 is equipped with a PureVideo HD decode engine that offloads large portions of the decode process for H.264, MPEG2, and VC-1 content. PureVideo HD leaves the number crunching associated with copy protection up to the CPU, but Nvidia claims the Atom is up to the task and that even a single-core Ion system should be able to play back Blu-ray movies smoothly.

Blu-ray playback may have limited utility for netbooks that typically don't come with optical drives or run enough pixels to display even 720p content at full resolution, but it's a must-have feature for a modern home theater PC. So is support for HDMI output, which the GeForce 9400 provides alongside VGA, DVI, and even DisplayPort video outs. And for those of you with fancy home theater receivers, the 9400 is also capable of passing multi-channel, uncompressed LPCM audio over HDMI.

The GeForce 9400's gravy train of goodness doesn't end at graphics, either. As one might expect from Nvidia's most recent motherboard GPU, the 9400 also has all the trappings of a cutting-edge core logic chipset. Take the memory controller, for example; it's a dual-channel design that works with either DDR2 or DDR3 memory. The Atom is hardly hungry for memory bandwidth, but Nvidia still hasn't held back any of the chipset's capabilities. That's why you'll find a whopping 20 second-generation PCI Express lanes lurking under the hood.

Perhaps more important than its ability to hook into PCI Express graphics cards and peripherals is the GeForce 9400's generous array of integrated peripherals. The chipset serves up six Serial ATA RAID ports, 12 USB ports, and even a Gigabit Ethernet port. That's probably more ports than most folks are going to need in a netbook or pint-sized desktop, but it certainly gives system designers plenty of options. At they won't have to farm out Gigabit Ethernet to a third-party peripheral chip.

Of course, the GeForce 9400 itself is not a small chip. You could fit several Atom cores within the confines of its die area. However, it's not as power-hungry as one might expect. Nvidia says the 9400's idle power consumption is just three watts—only one more than the 945GM/ICH7 chipset combo found in most Atom-based systems.