Atom for audio: this week, we’re mainly Asus


Despite continual revision of every aspect of the hard/software of our audio computers, an Intel Atom processor has been a constant in our computer audio recipe. Despite interesting competition from Via and AMD, a dual core Hyperthreading Atom CPU still provides the best power/weight ratio for this application.

Equally importantly, it’s the most efficient processor you can fit within the 3A envelope that sets practical and economical limits on the provision of low-ripple (sub-5uV average) power to the board, which may be the most critical component of a computer ‘transport’. Lower processing power sounds worse; higher input power sounds worse, too.

The Atom hits a sweet spot: not only we can juice it tidily, but – unlike smaller boards – we’re not limited to impractically small quantities of RAM (a single 4Gb stick is optimal) or banished to driver badlands where we can’t build a stable OS that support a wide range of DACs, or equip it with the right playback software. Windows XP occupies a similar Goldilocks position in the software universe:  lean enough to be quiet; compatible enough to be useful.

The other mandatory for the DAT1 (that ingenue CAPS!) has always been  deployment of the SOtM USB card. Now we have the PCIe version which contains a number of useful innovations – primarily the crucial move to USB3 – which motherboard provides the ideal base for a build similar to the DAT1?

If your budget for a DIY audio computer build, for a USB-specialist DAC, is around £1000 (£1500 for us to supply it ready made), we need a board that ticks the following boxes:
1: 32nm Atom Cedar Trail Processor supporting at least 2Gb RAM (ideally D2700 / 1333, but N-Series would be OK, too)
2: Multi-rail ATX input (not a single 12V with all that extra switching noise)
3: At least one PCIe slot

Ideally, the board would not have energy consuming integrated graphics chips above the spec of, say, an NM10. Simple is good.

Astonishingly, so far in 2012, an appropriate board simply hasn’t existed. For reasons that aren’t entirely clear, the increasingly unloved Atom processor has been paired with yesterday’s PCI bus in almost every commercially available board. OK – so tablets are replacing netbooks and meathead reviewers continue to slate mobo that aren’t big dumb ‘powerhouses’, regardless of their efficiency – but for our purposes, a dearth of Atom support is bad news. Driver support for XP and the desirable new Cedar Trail models is also patchy and not promised soon.

At the time of writing, only one board comes close to the right specification: the Zotac D2700ITXS A-E WiFi Supreme. Close, but no cigar: graphics too powerful and – worst of all – primary 12/5/3.3V switching right on the motherboard thanks for that pesky 12V single-rail input.

Until Intel release advertised replacements for their abortive first-generation Cedar Trail chips, and unless one of the major vendors (Gigabyte, while we’re wishing) pairs it with PCIe (6Gb SATA too, please Santa) and low-overhead graphics, we simply can’t recommend a Cedar Trail platform for an SOtM USB build: the PCIe version of their card trumps the PCI version, and a three-rail supply trumps a single-rail input.

In short, there’s only one board suitable: the Asus AT5IONT. It’s frankly overpriced, but (despite being based on the 45nm D525) remains the only viable solution. Initial versions of the DAT1 were actually based on this board: it impressed, but ironically got passed over because it opts for PCIe instead of PCI. Paired with the SOtM PCIe USB, that now makes it the front runner for audio computer builds at this price.

Funnily enough, Asus’ 1025CE is also currently the best netbook for audio and is therefore the basis of 2012’s Stealth Mini computer. Heck. Who are Asus distributed by now?


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