Introduction

The tech world has kept an interested eye on VIA's Nano since before the turn of the year, but the level of interest in the new processor has grown significantly in recent months, thanks in part to Intel's focus on the ultra-low-power/low-cost market. Over the past six months, VIA has found itself pushed from the perpetual twilight of an also-also-ran into a position of genuine competitive interest. The company is finally ready to sample Nano for performance testing, and I've had the opportunity to put the chip through its paces.

Atom vs. Nano: not a perfect match

In order to test VIA's new chip, I've benchmarked it against Intel's Atom. There's a lot of curiosity out there about how the two low-power processors stack up against each other, and this article attempts to satisfy that curiosity, but it's important to note that this is not an apples-to-apples comparison. According to Intel executive VP Sean Maloney, Atom is "built for low power and designed specifically for a new wave of Mobile Internet Devices and simple, low-cost PC's." As for Nano, VIA's whitepaper (PDF) states: "It [Nano] will initially power a range of ‘slim ‘n’ light’ notebooks." and "will also appear in ultra mobile mini-note devices and small form factor, green desktop systems for home and office use." In this case, we're benchmarking a Nano reference system at the upper end of VIA's product range. The L2100 CPU at the heart of the system is a single-core 1.8GHz processor, with a TDP of 25W.

Chip Design

Type Process Frequency

MHz SMT

FSB

MHz L2

cache TDP

(W) Intel Atom 230 In Order

45nm 1600 Yes 533

512K 4

VIA Nano L2100 Out-of-order 65nm

1800 No 800 1024K 25

While there is a certain degree of overlap between the two processors, it's limited to the relative upper end of Atom's target market and the relative lower end of Nano's. This might not seem so evident at the moment, given the limited number of Atom configurations Intel is currently selling on the DIY market (one), but the two products are focused in two different directions. There are other factors that cloud the comparison, including an early reference platform from VIA and a horribly mismatched processor+chipset combination from Intel, but I've done what I can to tease those differences out and present the two products from a variety of angles.

Performance summary

There are a number of different facets to consider when evaluating Atom vs. Nano, and that's a good thing for Intel. Were this simply a question of which CPU was faster, Nano would win, and by no small margin. Our benchmark results demonstrate that VIA's wunderkind is more than capable of competing in its target market; Nano beat the tar out of Atom in the majority of the tests we ran. The chip might have extended its lead further on a different platform; several tests indicated that the integrated S3 GPU was limiting total performance. Results are directly accessible from the links below. Anyone interested in the questionable effects of benchmark "optimization" should find the PCMark 2005 results of particular interest, while the DVD/HD content playback tests are one spot where the Atom + 945GC chipset pull well ahead of Nano's integrated GPU.

The entire point of these platforms, however, is that they don't focus on raw performance to the exclusion of all else. Power

efficiency is at least as important as raw speed these days, but how VIA and Intel rank in this area depends entirely on how we choose to

measure performance-per-watt (ppw). If we only consider processor TDP, Atom wins by a landslide. It may lose most benchmarks in

absolute terms, but it always remains competitive enough to easily win any power efficiency comparison. So, VIA wins absolute performance

but Intel wins power efficiency, right?

Wrong. Superman has Kryptonite, Rogue can't touch people, and Atom, for all its super-low TDP, has been effectively hamstrung by the 945GC chipset. With a TDP of 22W, Intel's chipset draws nearly six times more power than the processor itself, a fact that's driven home when you realize that the tall heatsink + fan combination on the retail D945GCLF board is actually cooling the northbridge, rather than the CPU.

The power-hungry nature of its platform destroys any current chance Atom had of establishing itself as a truly low-power alternative. Total system power draw is still quite low by desktop standards, but the D945GCLF's maximum load power of 59W is only about nine percent lower than VIA's reference motherboard. That narrow discrepancy isn't enough to offset VIA's sizeable performance advantage in many benchmarks, and the Nano ends with a higher overall, platform-level performance-per-watt ratio than Atom in many of our benchmark tests.

The bottom line

Nano is an excellent step forward for VIA. It's by far the most compelling CPU the company has ever launched, and could potentially carve a spot for itself in its target market segments. VIA's mini-ITX reference platform is similarly impressive; the board's PCIe x16 slot opens the door for a variety of potential applications that the Atom reference platform can only dream about. Intel's D945GCLF may run just $75 for a 1.6GHz HyperThreaded Atom processor, but it's painfully obvious that the board was designed with an eye towards guarding Celeron sales, and the lack of expansion capabilities hurts Atom's overall attractiveness.

VIA's CN896 chipset may be a better overall fit for Nano, but the integrated Chrome9 HC graphics solution leaves much to be desired. While it proves marginally faster than Intel's GMA950 in some tests, it slumps badly when asked to decode much of anything. The built-in PCIe x16 slot significantly addresses this issue, but the availability of an expansion slot, in and of itself, does not compensate for lousy integrated video—even on a netbook-class solution.

There are too many long-term questions across too many areas to deem this a complete slam-dunk for VIA. Reviewer samples and reference platforms are great for publicity, but VIA has yet to demonstrate that it can ship Nano boards and chipsets in volume. The company has promised that mini-ITX Nano boards will be available in the retail channel by the end of the third quarter, so we should know in a few months if the company can make good on its promise of availability. The fact that Nano is a drop-in replacement for C7 could make the chip attractive to manufacturers with C7-based devices, but again, neither VIA nor its partners have announced plans in this area. A few words from HP confirming Nano as a basis for an upcoming refresh of the 2133 would do wonders for both Nano sales and VIA's reputation.

The largest potential barrier to Nano's long-term success, of course, is Intel. Santa Clara has made no secret of the fact that it believes MIDs, netbooks, and nettops are the future of the industry, and that it intends to offer an Atom that could fit inside any of these devices. Right now that might sound laughable, but Intel isn't kidding. The company's current retail Atom 230-based board might not be what you'd call compelling, but that doesn't mean that future products won't be. VIA's long-term success will be directly proportional to the number of design wins the company can gather for itself in an area Intel has announced it intends to dominate long term.