Compared: VIA Nano CPU vs Intel Atom

Nano chip
VIA's Nano chip has speed on its side

The launch of Intel's low-power Atom processor earlier this year has been something of a reality check for the computer industry. For decades, most CPUs have been sold pretty much exclusively on performance. You simply bought the fastest chip your budget allowed.

Then Atom came along, said "stuff that" and unapologetically offered merely adequate performance. No nonsense about blazing multimedia performance. Just a cheap chip that gets the job done for most people, most of the time.

It's enough to make you wonder whether you've been blindly blowing way too much money on your PCs. If Atom is "good enough", who needs a pricey Core 2 processor?

Mixed messaging

In fact, Atom is such a departure from the norm even Intel's usually slick marketing operation has been struggling to keep on message. Rather bizarrely, Intel's head honcho Paul Otellini recently described the Atom as a chip that, "most of us wouldn't use."

It's into this intriguing context that plucky old VIA is launching its latest low cost CPU, the Nano. Unlike most CPUs from VIA, which typically lag behind in the performance stakes, extremely bullish noises are being made about the Nano.

Put simply, VIA reckons it's faster across the board than the Atom. Certainly, it's a more sophisticated chip than the cut-down Atom. It's a fully x86-compliant design and crucially supports out-of-order execution. The Atom is a simple in-order chip and therefore very compact but relatively inefficient in terms of work done per clock cycle.

Fine architecture

The Nano has a range of further architectural advantages such as the ability to issue three instructions per clock cycle to the Atom's two. All Nanos also support 64-bit data addressing, a feature currently only offered by a single Atom model.

In fact, the Nano's only obvious shortcoming is the lack of support for simultaneous multi-threading – Atoms, of course, support two threads courtesy of Intel's HyperThreading technology.

All in all, therefore, the Nano architecture looks like it should be capable of significantly more number crunching per clock cycle than an Atom. The Nano is also available at slightly higher frequencies. Conclusion? It jolly well ought to offer more performance.

Power consumption

The other half of the equation is power consumption. Here things look a little less auspicious for VIA's new cheapo chip. On paper, the Atom is much, much more power efficient. Intel says the maximum power consumption of any Atom is below five watts, whereas the top Nano is a 25 watt chip.

Granted, VIA and Intel measure power consumption slightly differently. But not that differently. Clearly the Nano's more complex architecture comes at a power efficiency cost. For cheap desktop systems, that probably doesn't matter. However, for low cost netbooks and notebooks, the Nano's relative gluttony could be a significant drawback, both in terms of battery life and form factors.

Anyhow, what you really want to know is how the Nano performs. Happily, that's a question we can answer. We have both the top 1.8GHz Nano L2100 and Intel's 1.6GHz Atom 230 to hand and it makes for an extremely interesting contest. Both are desktop chips aimed at so-called net-top systems.

Restrict your activities to simple web browsing or low key document editing and there's not much to choose between the two. Both are capable of running a full fat install of Microsoft's bloated Vista operating system reasonably well.

Yes, the shiny Vista interface is a little less responsive than with a Core 2 processor or one of AMD's desktop chips. But so long as you keep the open browser page count to sensible proportions, both the Nano and Atom can cope.

Advantage VIA

However, fire up more demanding applications and the Nano's superior grunt does begin to tell. In truth, the Nano's performance doesn't quite live up to VIA's claims when it comes to video decoding. The Nano simply can't cope with really demanding video codecs such as H.264 at HD resolutions.

Granted, it makes a reasonable fist of WMV content at 720p. And importantly, it handles high quality streaming web video, such as the BBC iPlayer with around 50 per cent of CPU resources to spare.

But overall, it's not a great chip for high quality multimedia malarkey. The fact that the Atom struggles even more with HD video (but oddly performs comparably for streaming web video) doesn't really help.

More useful is the Nano's all-round performance advantage of approximately 25 - 30 per cent. If you are occasionally dipping into demanding applications, there's no question which chip is the better choice.

Sadly, the question we cannot answer definitively, for now at least, is that of comparative power consumption. Our early Nano reference board refused to boot courtesy of its integrated graphics, forcing the use of a plug-in PCI Express graphics card.

The Atom net-top system we have lacks support for discrete graphics, so a like for like comparison isn't possible.

V is for victory?

Nevertheless, as a desktop chip where power consumption is not a major factor VIA's Nano certainly looks promising. Assuming similar pricing (typically these CPUs will be bought as part of a system rather than as a stand alone purchase), we'd certainly take the Nano for its superior performance.

Whether the Nano can compete in the arguably more interesting netbook segment, however, remains to be seen.

VIA Nano L2100

  • Cinebench R10: 13mins 51secs
  • H.264 video encode: 5fps
  • Memory bandwidth: 2.75GB
  • Sandra integer test: 5,007MIP
  • Sandra Floating point test: 26,505fit
  • Windows Vista boot time: 1min 5sec
  • 720p H.264 video decode: Fail
  • 720p WMV video decode: Smooth, 50% CPU time
  • BBC iPlayer video decode: Smooth, 55% CPU time

Intel Atom 230

  • Cinebench R10: 18mins 01secs
  • H.264 video encode: 4fps
  • Memory bandwidth: 1.93GB
  • Sandra integer test: 3,853MIP
  • Sandra Floating point test: 19,797fit
  • Windows Vista boot time: 1min 20sec
  • 720p H.264 video decode: Fail
  • 720p WMV video decode: Smooth, 40-60% CPU time
  • BBC iPlayer video decode: Smooth, 60% CPU time

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