Intel Atom CPU Review

Atom Z500 and SCH (Poulsbo)

The first generation of Atoms is the Z5x0, previously known by the code name Silverthorne. The Atom Z500s are dedicated to MIDs (the famous Mobile Internet Devices) and are coupled to a new chipset, the Poulsbo SCH (System Controller Hub).

Atom Z500: Competition for ARM CPUs?

intel atom

With the MID orientation, it’s clear to see who Intel’s target is – ARM processors. This very popular architecture (it’s used in the great majority of telephones, PDAs, and GPS devices) is offered by many manufacturers (ARM licenses its instruction set) and offers good performance while keeping power consumption low. In the mobility arena, except for a few rare devices using MIPS architecture (the PSP, for example), ARM processors are in the majority. Intel, incidentally, once produced ARM CPUs for consumer applications (the XScale, since sold to Marvell) and still has a line of products used, for example in RAID cards (the IOP333, for example). In practice, moving from an ARM architecture to x86 poses no real problems – Linux is obviously compatible, as are Windows CE (used in many GPSs) and the Windows Mobile OS layer (at least in the older versions). In addition, the x86 can also make use of the latest Windows versions and so benefit from broader software (and technical) support than with ARM CPUs.

The Z500 Processors

intel atom

Before we analyze the architecture of the Atom, let’s look at the Z500 series. These processors are very small, delivered in a package only 13 x 14 mm. The processors are made up of approximately 47 million transistors (more than the original Pentium 4) and have 56 kB of Level-1 cache (24 kB for data and 32 kB for instructions) and 512 kB of Level-2 cache. They operate on a standard Intel bus, the same one used since the Pentium 4. The frequency of the bus is 400 MHz (QDR) or 533 MHz (QDR). There is also support for SIMD instructions, from MMX to SSSE3, EIST, and HyperThreading (making its comeback). Note that the latter technology is available only on certain models (with the 533 MHz QDR bus).

Poulsbo, A Chipset for the Atom

intel atom

The SCH (System Controller Hub) is a chipset that includes the Northbridge and Southbridge in the same chip. Dedicated to Atom processors, it is the only one compatible with certain functions such as using the bus in CMOS mode (we’ll talk about that later). The SCH is complete – it includes a GMA graphics circuit (based on a PowerVR architecture), an HD Audio circuit (simplified, capable of operating only in two channels), a P-ATA controller (Ultra DMA 5, 100 MB/s), and supports two PCI-Express lanes (for a Wi-Fi card, for example). There are also three SDIO/MMC controllers and support for 8 USB ports (with the possibility of using one in client mode). The choice of P-ATA is logical: The controllers used in flash memory are often in this format (used by Compact Flash cards). Three SD controllers might seem strange, but certain types of memory use that connectivity (OneNAND, for example). Also, the DDR2 controller of the SCH supports memory with a voltage of 1.5 V (as opposed to 1.8 V for the JEDEC specifications). This little detail is a way of further reducing power consumption.

The Graphics End of Poulsbo

On the graphics side there’s a new GMA, the GMA 500. It uses a unified architecture and supports 3.0+ Shaders. An interesting point is that it has hardware support for decoding of the H.264, MPEG2, MPEG4, VC1, and WMV9 formats. The frequency of the GMA 500 is 200 MHz or 100 MHz, depending on the chipset version, and it’s DirectX 10 compatible (not really useful, but worth mentioning), even though the drivers only support DirectX 9. Note that the graphics end is not of Intel origin, but uses a PowerVR technology, unlike other GMA models.

intel atom

An Interesting TDP

The Atom Z500 has a TDP that varies between 0.85 W (for the 800 MHz version without HyperThreading) and 2.64 W (for the 1.86 GHz model with HyperThreading enabled). The SCH consumes approximately 2.3 W in its most evolved version, which brings the SCH + CPU together to under 5 W. By comparison with existing solutions, that’s obviously a big step forward – the Via Nano, for example, is announced at 25 W for the 1.8 GHz version and a Celeron-M ULV at 5 W at 900 MHz.

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  • anonymous x
    wow, 107 on 3D mark06
  • joefriday
    Celerons have significantly lower frequencies than Atom? Only the ULV celeron M has a lower freqency. Modern notebooks start with Celerons at least 1.6GHz, more likely 1.86GHz, and are built on the much more modern Merom architecture, which have at least a 10% IPC advantage over the old Dothan architecture. No, atom is nowhere NEAR a modern Celeron in performance. Nice try though.
  • joefriday
    Also, Why not have a Celeron 420 by now? Are you telling me that THG, with all its money, can't budget in a $30 CPU for comparative testing?
  • joefriday
    After reviewing the article, I can say I'm thoroughly unimpressed with the Atom platform (at least the current desktop derivative). If anyone can remember, THG did a $300 PC build using now ancient Celeron Ds and AMD Semprons. One thing that I find amazing, is that those old rigs both use LESS power than this Atom desktop rig.,1546-10.html

  • randomizer
    Don't you people understand that Atom is not a desktop processor? You can't compare its performance to a desktop processor fairly because that's not what it is designed for.
  • joefriday
    This Atom CPU is on a desktop board. That means it's fair game, especially when the processors being compared are also comparable in price.
  • randomizer
    It's on a desktop board, woopdedoo. If you could get your mobile phone processor to run on a desktop board would you compare it to an E2160?
  • joefriday
    Who cares what the Atom CPU is SUPPOSED to be. It is right now, in this review, on a desktop-oriented package, built to compete with low power consumption desktop computers. It fails miserably in that regard, as it is neither low power consumption, nor competitive. In your ridiculous example, if I had a mobile phone processor on a desktop board, and it ended up consuming more power than an E2160/motherboard combo that costs the same amount of money, all the while performing much worse than the e2160, I would call the mobile phone cpu on a desktop motherboard either A FAILURE or AMD. Take your pick.
  • apaige
    So, for the Intel Atom, you do use an updated version of Sandra, but not for the Phenom. You compare it to the VIA C7, a 3 year-old CPU, but not the VIA Nano, which will be available in the same timeframe as the Atom. You don't provide graphics for power consumption, despite the Atom being designed for low power consumption; surprise, the old C7-M system draws less power.

    Biased much?
  • Anonymous
    Not sure that Nano's are really available yet, still a newer mini-itx based C7 (say EPIA-M700) would have been better, since you would be looking at even less power than the one used and the VX800 will end up used with the Nano. The D201DLY[2] would have been good to compare to, would also give some idea how the Atom would go paired with SiS chipsets.
  • Crazy-PC
    Why not benchmark with other mobile CPUs like Intel X-scale and the mobile CPU from TI etc Atom would be more make sense to use on small mobile device rather than notebook.
  • Anonymous
    randomizerDon't you people understand that Atom is not a desktop processor? You can't compare its performance to a desktop processor fairly because that's not what it is designed for.

    His point was that it's not only less powerful than "comparable" desktop CPUs, it also takes more power, which pretty much defeats the meaning of being used as a CPU in portable applications. His point is that this CPU is unimpressive in every area you could apply it versus what's already there. Nice try, Intel.
  • Anonymous
    VIA Nano powered by Nvidia GPU in mini-itx play game: Crysis and Bioshock.
  • Anonymous
    ??? INTEL ATOM vs. VIA NANO ???
  • Wheat_Thins
    Where the heck is the performance / watt comparisons. The entire point of this processors creation is performance / watt and its missing from your benchmarks! Please Add!
  • mmc4587
    Dude, please correct your Cinebench R10 charts, they are screwed up.
  • joefriday
    His point was that it's not only less powerful than "comparable" desktop CPUs, it also takes more power, which pretty much defeats the meaning of being used as a CPU in portable applications. His point is that this CPU is unimpressive in every area you could apply it versus what's already there. Nice try, Intel.

    Don't get me wrong...I do think the Atom probably has a decent performance per watt for the CPU itself, but this platform being tested, the entire rig, is where it disappoints. I don't know if it's all in the PSU inefficiency or what, as Anandtech's review of the ASUS Eee Box put power consumption at below 20 watts under load, using a seemingly comparable hardware list (but with a DC power brick, instead of a conventional power supply).
  • enewmen
    Good article.
    Still don't know if it's POSSIBLE to run Vista64 on a Atom.
    I'll wait for the next-gen of eee PC clones. Then I'll get a better idea of real-world performance.
  • Anonymous
    NVIDIA Tegra is much Better
    It would be interesting to see their response at the Intel Atom Processor Launch Event on June 3rd, 2008*. In the meantime, let's take a look at what the NVIDIA Tegra is all about... why ? lets see
    * an 800 MHz ARM CPU,
    * a HD video processor,
    * an imaging processor,
    * an audio processor,
    * and an ultra-low power GeForce GPU
    for father information plz go to
  • doomsdaydave11
    Yay the Poulsbo processor is named after where I live :D. There is only one Poulsbo... so it must be. I'ma go out and buy one now. ;)