The following components were identical between both testbeds.
- Acer AL2216W 22" 1680x1050 LCD.
- Seagate Barracude 7200.9 250GB HDD
- 2GB OCZ DDR2-1066 @ DDR533
- Windows XP w/SP3 installed
- Enermax 250W PSU
Our VIA reference board consisted of a VIA Nano combined with the CN896 northbridge. More information on the northbridge can be found over at the company's website, but the board we tested is a full implementation, with two DIMM slots and a single PCIe x16 slot. As for Intel's Atom, the company currently offers just one SKU on the retail market. Details on the Atom 230-based D945GCLF are available here.
It doesn't take Nancy Drew's insight to see that these are two very different products. The Nano board is full-featured for a mini-ITX product, with two DIMM slots and a PCIe x16 slot, while the Atom-based D945GCLF can scarcely be expanded at all. Intel makes a limp-wristed token gesture to expansion with a single PCI slot, but the highly integrated nature of the board, combined with the extremely limited performance of PCI, leaves me wondering why the company bothered. As I'll explore, Atom's limited expansion does impact the board's attractiveness, even when judged solely by the standard of its target low-end market. Both systems were tested with 2GB of RAM, and both are limited to a single, 64-bit memory channel.
As I mentioned earlier, the large heatsink+fan on top of the Atom board is cooling the chipset, not the CPU. The fan itself isn't audible unless you literally put your ear up to it. Neither the Atom nor the Nano testbed produced any noise above a simple operating hum unless a CD was spinning up in one of the drives.The largish fan on VIA's reference board is an integrated solution that covers both northbridge and CPU, with a separate heatsink for the southbridge.
I debated between Windows XP and Windows Vista, but eventually settled on XP as the better fit for these type of systems. The LCDs I used both support 1680x1050 resolutions, but Worldbench 5 runs all of its tests in 1024x768 by default. This seemed a reasonable resolution for the systems anyway, so I kept it for all further performance testing. The one exception was when I tested HD content playback—I pushed both monitors up to 1680x1050 when measuring DVD, HD DVD, and MPEG-2 performance.
As for the benchmarks themselves, I chose a suite of older tests that could measure system performance without requiring Vista or requiring more than 2GB of total RAM. Tests like Cinebench and PCMark aren't strictly representative of likely workloads, at least not in the netbook market, but they provide additional subsystem performance information. Ultimately, I think we'll see a new series of MID and netbook-specific tests emerge as this market matures.
One final note before we turn to benchmarks. Although I haven't broken the results out here, I ran a number of tests with HyperThreading disabled, in order to judge how much of a performance boost Atom gained from the feature. Back in the Netburst days, Intel targeted a ~20 percent performance increase with HT enabled over HT disabled in an appropriately threaded test, but that was years ago, and a very different architecture. Atom is an in-order architecture, and as such, is potentially vulnerable to stalling out. HT could potentially help the processor keep its pipeline full by seeding the execution units with additional uops.
Based on what I saw, HyperThreading plays a major role in keeping Atom data crunching. Exact results varied from application to application, but enabling HT often boosted performance by around 50 percent. Almost all of the Atom SKUs Intel has announced will offer HyperThreading; it seems to be an essential part of the secret sauce that keeps Atom (somewhat) competitive.
The other advantage of HT is the way it smoothes system responsiveness. The Nano might be faster than the Atom, but the chip suffers from the same small stutters and tiny pauses that impacts all single-core processors when the OS is busy doing other things. Thanks to HyperThreading, Atom feels smoother, and the system remains more responsive while engaged in other tasks. This effect is something of an optical illusion, since a system that finishes a task more quickly can move on more rapidly to do something else, but it does give Intel's new core a perceived advantage.