Atom takes the Pine Trail
As you may have gathered, Brazos' most natural competitor is Intel's Atom processor, specifically the version aimed at netbooks and compact desktop systems (which Intel calls "nettops.") The latest Atom platform in that category is code-named Pine Trail, and the CPU at the center of it was developed under the name Pineview, just to keep the pine-scented confusion swirling. The Pineview Atom is remarkably similar to Zacate, incorporating one or two low-power CPU cores, an IGP, a memory controller, and an interconnect to a separate I/O chip. (We first covered the platform in some depth here.) At 87 mm² and 66 mm², respectively, the dual- and single-core variants of Pineview bracket the 75 mm² Zacate in size.
Pineview's CPU cores use a simpler in-order execution scheme, but unlike Bobcat, each core can track and execute two threads simultaneously. The Atom's architects chose symmetric multithreading rather than out-of-order execution as a means of achieving higher per-clock performance, and so far, that's proven to be a pretty good bet. SMT, better known at Hyper-Threading in Intel's marketing lexicon, is most helpful at some of the toughest points of everyday PC use, such as periods of heavy multitasking or when dealing with media playback and manipulation.
The integrated GMA 3150 graphics core looks to be less formidable, based as it is on a rather old Intel chipset IGP. Raw graphics power is one of its weaknesses, but more critically, the Pineview IGP supports only the most rudimentary version of DirectX 9, known as Shader Model 2.0. Even there, the IGP lacks support for some texture formats available in the first DX9/SM2.0 GPUs like the Radeon 9700. Thus, even if Intel's graphics drivers were a model of quality and compatibility, the GMA 3150 would fall short of the minimum requirements for great many games.
That's a shame, but the worst part of the story, as we've noted, is that fact that Pineview's video processing logic can't accelerate the decoding of H.264 video, so that burden will fall entirely on the Atom CPU.
One other difference between Zacate and Pineview is the memory controllers. Although both support a single DRAM channel, Pineview's support is limited to DDR2 memory at a peak of 800MHz. Performance-wise, that's not likely to amount to much of a difference versus Zacate's 1066MHz DDR3 channel, but it may mean more on the power front due to DDR3's lower operating voltages, particularly because Zacate supports low-voltage variants of DDR3 memory.
While searching through the Newegg listings for an appropriate product to compare against the MSI Brazos board, we came across this unassuming offering from Jetway for $130. This board has several things we wanted. It's based on the Pine Trail platform with an Atom D525 processor, the fastest desktop/nettop version of Pineview. The D525's two CPU cores run at 1.8GHz, and the whole chip has a TDP of just 13W, a little lower than Zacate's 18W. Like the MSI Brazos board, the Jetway has a PCIe x16 slot, raising the threat of a discrete graphics card. Although many folks would likely cite Nvidia's second-gen Ion platform—essentially Pine Trail plus a small discrete GPU—as Brazos' most appropriate foil, we wanted to see how AMD's latest stacks up directly against Intel's total platform solution, which is more widely used than Ion. Of course, this Pine Trail setup can easily be augmented with any discrete GPU we might choose to drop into its PCIe x16 slot, as well.
Finding a Mini-ITX board with an Atom D525 and a PCIe x16 slot isn't easy, and we had to make a few compromises. We're not so pleased with the Jetway's lack of digital audio and video outputs, for instance. Still, the totally passive cooling on the board is nifty, and the expansion slot allows us to overcome both of those output shortcomings via a single HDMI port.
The final implements of destruction
Our nefarious plan to compare these low-power platforms to one another and, scandalously, to standard desktop systems requires a few more tools.
One of those is a low-end discrete graphics card, with which we can test AMD's claim that Zacate includes "discrete level" graphics. Pictured above is a Radeon HD 5450, shamelessly stuffed into the PCIe slot on our MSI Brazos board. Although a great many Brazos systems will no doubt use the IGP, this card will allow us a nice basis of comparsion for the graphics component alone. We can also see how the Atom D525 might fare if it were granted the assistance of a Radeon GPU.
More questionably, we populated both boards' PCIe slots with a more powerful graphics card—a GeForce GTX 460 1GB—for the portion of our comparison that includes full-scale desktop processors. Doing so meant all of the CPUs involved would be working with the same GPU, although we should point out that the Atom and Brazos systems have only four lanes connected to their PCIe x16 slots. We'll probably lose our license over this.
Both of our Mini-ITX contestants proved to be perfectly happy when connected to the 610W Silencer PSU that's standard issue for our CPU test rigs, but we couldn't really address the question of power efficiency when using a power supply intended to deliver well over ten times the juice that our itty-bitty integrated systems require at peak. That's why we ordered up the power supply you see pictured above, the nMediaPC HTPC 1080iP. This puppy has a max power rating of 85W, supplied by a completely passive, laptop-style power brick that plugs into a break-out PCB with standard ATX-style connectors.
Using it with the passively cooled Jetway Atom board, the Radeon HD 5450 shown above, and a Corsair SSD produced some freaky, "Is it on?" moments, because there was virtually no sound whatsoever emanating from the computer as it POSTed, booted, and ran programs. We achieved a similar effect, at least part of the time, by setting the MSI board's minimum CPU fan speed to 0% and giving it a relatively high 65° C target temperature.