AMD Fusion - Brazos Motherboards Tested!

AMD Brazos - The Atom Killer?

AMD Brazos - The Atom Killer?

Yes, we know that 'killer' is probably one of the most overused word in the tech industry, but the first concrete example of AMD's Fusion initiative, the Brazos platform is exactly that. With a low power envelope of 18W TDP for the dual-core version, Zacate (or E-Series) and just 9W for the single-core Ontario (C-Series), it is the closest that AMD has come to matching Intel's Atom platform in terms of power consumption. It means that AMD may finally have a low-power chip able to fit into the netbooks and nettops segment that has been long dominated by Intel's Atom. For the full story behind Fusion, market segmentation and more primer information, do check out our Fusion 101 article.

The reason for AMD's optimism is the inclusion of a DirectX 11 capable GPU integrated as part of the CPU die (henceforth renamed as APU or Accelerated Processing Unit). Just like Sandy Bridge? Exactly, except that AMD was arguably first with this concept. Ever since it bought over graphics chipmaker ATI in 2006, Fusion has been mooted as a way forward for the new combined entity. After many delays and setbacks, Fusion is finally a reality and it is represented today by the dual-core Zacate. The Zacate and the other models in the Brazos/Ontario family are listed below:

Model Cores Clock Speed GPU TDP
E-350 (Zacate) 2 1.6GHz Radeon HD 6310 18W
E-240 (Zacate) 1 1.5GHz Radeon HD 6310 18W
C-50 (Ontario) 2 1.0GHz Radeon HD 6250 9W
C-30 (Ontario) 1 1.2GHz Radeon HD 6250 9W

Based on the Bobcat architecture, which features a 64-bit out-of-order core with a 32KB L1 instruction cache, a 32KB L1 data cache and a 512KB L2, the 40nm Zacate consists of two such cores running at 1.6GHz. Instructions from SSE to SSSE3 are supported, though the newer ones like Intel's AVX obviously are not.

Its GPU component is made up by two SIMD with 40 stream processors each. It is a derivative of AMD's Cedar-class (~ Radeon HD 5450) of DX11 GPU, with a new Unified Video Decoder (UVD3) that can support hardware acceleration for DivX and Xvid. AMD calls it the Radeon HD 6310 and it comes with a default clock of 500MHz. The lower version, the HD 6250 has roughly half the clock speed at 280MHz. You can find out more about the architectural details of the new APU here.

As mentioned, its low power consumption with a 18W TDP is one of the advantages that AMD is keen to talk about, and this is possible due to clock and power gating technologies. While we are more likely to find them in netbooks and even ultra-portable entry-level notebooks, we'll be testing the Brazos platform first on three similar mini-ITX motherboards (with the Zacate chip embedded onboard) that are meant for enthusiasts looking to hook up a low-cost desktop or HTPC.

 This small chip is the Zacate dual-core APU, manufactured using a 40nm process and with a low TDP of 18W.

The 1.6GHz Zacate is part of AMD's Bobcat CPU architecture.

Paired with the Zacate APU is the AMD Hudson M1 (A50M) chipset or Fusion Controller Hub (FCH). It's connected to the Zacate APU though a 4-lane Gen 1.0 Unified Media Interface. With support for up to six SATA 6Gbps devices, four PCIe 2.0 lanes, HD audio and the usual plethora of USB 2.0 devices (14 to be exact), it's decent enough for its market segment, though more powerful APU variants in the future will require a correspondingly buffed up chipset that should ideally have more PCIe 2.0 lanes, Gigabit Ethernet and even USB 3.0 support.  

The AMD Hudson chipset that provides the SATA 6Gbps support, PCIe 2.0 lanes and the USB ports looks even smaller than the Zacate APU, though it's manufactured on a 65nm process.

Moving on, click on the next page to read about the first of our three AMD Brazos motherboards, the ASRock E350M1.

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