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Power Consumption

AMD Athlon II X2 / Phenom II X2 And Low-Power CPU Bonanza
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All of our benchmarks were run with power-saving features enabled. AMD actually weighed in just after the entire suite had been completed to recommend against testing this way because, currently, the two cores on its Athlon II X2 are changing P-states independently. An upcoming BIOS code update will have both cores shifting P-states together. The problem with independent switching, according to AMD, is that single-threaded workloads with a tendency to hop from one core to the other will experience a slow-down due to operating system scheduling inefficiencies.

This phenomenon is best-illustrated with an example. If you have two cores and are running a Lame .mp3 encode, then one thread is idle (since the encoder is only single-threaded). Scaling that idle core back to 800 MHz while the utilized core does its work at 3 GHz helps cut back on power, reduce heat, and so on. But if Vista’s scheduler bounced Lame over to the idle core running at 800 MHz, you’d incur a significant performance impact all of the sudden. While it is common to see a single thread of Prime95 bouncing all over the place, I kept an eye on Lame and WinZip and am fairly positive these apps weren’t getting affected by this potential issue.

AMD’s implementation is the “right” way to go about optimizing for efficiency, but it’s hampered by Microsoft. Phenom II “fixed” this behavior by keeping all cores running at the same speed. If I understand AMD correctly, the upcoming BIOS will shift from Phenom- to Phenom II-like operation. With all of that said, testing with Cool’n’Quiet enabled works to AMD’s benefit when it comes time to measure power, since all of these CPUs are able to throttle down to 800 MHz while they idle.

The company’s low-power quad- and triple-core CPUs are its most impressive. They consume just about as much power as the Phenom II X2 at idle, but use less than even the 65 W Athlon II X2 under load.

Intel’s Core 2 Quad Q8400 and Pentium E6300 actually serve up even better idle numbers. However, the Core 2 Quad ends up using about as much power as AMD’s 80 W Phenom II X2 under load (not bad considering the Intel chip is rated at a 95 W TDP).

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  • 28 Hide
    thedipper , June 2, 2009 1:45 AM
    IronRyan21Maybe if AMD would actually bring out some kind of nehalem competitor instead of flooding the cheapo market with variations of the same chips all over the place. There was Athlon 64 X2, brisbane and windsor, then there was Kuma, which was a phenom with 2 cores disabled. Now we got these new chips which are phenom 2s with 2 cores disabled. Lets put the money into some R&D and get somewhere. It seems like AMDs lost traction. sad.


    The low to mid-price segments are the best selling hardware categories.

    Believe it or not, the $100 bang-for-the-buck graphics cards by far outsell the $500 space heater graphics cards. As with graphics cards, $50-100 CPUs by far outsell the $300-1300 CPUs.

    The market that seems like most of the market - the enthusiasts and gamers - is actually not that much of the market share. Businesses building for performance-per-dollar, low-mid performance factory built home PCs, and people building web or media machines... these together outweigh the enthusiast/gamer market.
  • 18 Hide
    Anonymous , June 2, 2009 1:58 AM
    @IronRyan: Why not start your own semiconductor company and show AMD how it's done? Can a similar argument not be applied to Intel's "double cheeseburger" quads, and "single patty" dual-cores? If we even get any non-quad i7/i5s, do you know if Intel won't just do the same thing? In the future, instead of coming up with some lame argument, just post this for each article:

    "Hi, my name's IronRyan, and I like Intel. Go team Intel, yay!!!!!"
Other Comments
  • 28 Hide
    thedipper , June 2, 2009 1:45 AM
    IronRyan21Maybe if AMD would actually bring out some kind of nehalem competitor instead of flooding the cheapo market with variations of the same chips all over the place. There was Athlon 64 X2, brisbane and windsor, then there was Kuma, which was a phenom with 2 cores disabled. Now we got these new chips which are phenom 2s with 2 cores disabled. Lets put the money into some R&D and get somewhere. It seems like AMDs lost traction. sad.


    The low to mid-price segments are the best selling hardware categories.

    Believe it or not, the $100 bang-for-the-buck graphics cards by far outsell the $500 space heater graphics cards. As with graphics cards, $50-100 CPUs by far outsell the $300-1300 CPUs.

    The market that seems like most of the market - the enthusiasts and gamers - is actually not that much of the market share. Businesses building for performance-per-dollar, low-mid performance factory built home PCs, and people building web or media machines... these together outweigh the enthusiast/gamer market.
  • 9 Hide
    jj463rd , June 2, 2009 1:48 AM
    Those Phenom II 905e's and 705e's would be kickass if paired with the upcoming 785g motherboards.
    AMD has some new interesting CPU's.
  • 18 Hide
    Anonymous , June 2, 2009 1:58 AM
    @IronRyan: Why not start your own semiconductor company and show AMD how it's done? Can a similar argument not be applied to Intel's "double cheeseburger" quads, and "single patty" dual-cores? If we even get any non-quad i7/i5s, do you know if Intel won't just do the same thing? In the future, instead of coming up with some lame argument, just post this for each article:

    "Hi, my name's IronRyan, and I like Intel. Go team Intel, yay!!!!!"
  • 9 Hide
    deputc26 , June 2, 2009 2:09 AM
    Anyone else see the Athlon X2 and think that if they underclocked and undervolted it they'd finally have a legitimate mobile contender?
    If they can run 4 cores at 2.5ghz and 8mb cache on 65w they should be able to run 2 cores at 2.5 ghz and 2mb cache at less than 32.5w.
  • 2 Hide
    rdawise , June 2, 2009 2:33 AM
    Interesting article...I'm glad you put this against the E6300. I haven't seen much about this chip. It as if Intel just snuck on onto the market. I wonder how high of an overclock you can get with it....

    Onto the article, it seems as if the Phenom II x2 550 BE would a great chip in a value gaming rig. If you could unclock the extra cores and get it stable, you'd be one lucky man. Can't wait till see these on the Egg...
  • 0 Hide
    cangelini , June 2, 2009 2:38 AM
    Quickest Pentium, only one with a 1066 MHz bus, disappointing that it's missing some functionality, though.

    Anyone else reminded of GeForce 2 MX when they see how Intel is positioning its mainstream chips these days? I'm all for differentiating with performance to drive down price (even cutting performance-oriented features, like Hyper-Threading), but don't start shedding the actual capabilities of an architecture to handicap it.
  • 2 Hide
    Anonymous , June 2, 2009 3:14 AM
    I would find the Phenom X2 550 interesting because many of the programs I still run today are singlethreaded.
    These programs benefit more from a higher clockrate than more cores.

    Keeping this in mind, and the fact that an OS doesn't (spectacularly) boot faster with more cores, I think the X2 is a great buy.
    I'm a bit dissapointed at the powerdraw. For a HDTV box you don't necessarily need to buy a Radeon 4850. Perhaps a lower powerdraw (and price) in the 4770 or 4670 will be better.
    To playback full HD (1080p) I suppose a Radeon HD 2900XT would be enough.
    Add office tasks, internetting, some photoshop, and casual gaming on a 22"monitor (1680x1050 pix), and a Radeon 4670 would be enough in most cases.
    If you have a 24" monitor (1920x1200 pix) a Radeon 4770 would do.
    Only when latest gaming is concerned should you go for a Radeon 4870 or a 4890.
  • -2 Hide
    Gin Fushicho , June 2, 2009 3:16 AM
    Cant...wait...for...AthlonII.
  • 0 Hide
    cangelini , June 2, 2009 3:24 AM
    Pro, for an HTPC, you'd be fine with a 4670, more than likely. The challenge will be building a system able to keep that setup cool enough. The Maui box with the 905e was *near-silent* but a discrete card would have wrecked this, and a 4670 is almost too much card to be passively-cooled (a la Ultimate-style) without better airflow in the case.
  • 0 Hide
    billybobs , June 2, 2009 3:27 AM
    IronRyansSister@IronRyan: Why not start your own semiconductor company and show AMD how it's done? Can a similar argument not be applied to Intel's "double cheeseburger" quads, and "single patty" dual-cores? If we even get any non-quad i7/i5s, do you know if Intel won't just do the same thing? In the future, instead of coming up with some lame argument, just post this for each article:"Hi, my name's IronRyan, and I like Intel. Go team Intel, yay!!!!!"


    Is this guy serious? He counters another reader's argument by taunting him? Seriously.
  • -3 Hide
    WheelsOfConfusion , June 2, 2009 3:35 AM
    Huh, I had assumed that the new Athlon line was just going to be Phenom IIs with cache/cores disabled. I guess this dedicated design is just a more efficient way to sell silicon than disabling good chips?
  • 1 Hide
    rooseveltdon , June 2, 2009 3:36 AM
    billybobsIs this guy serious? He counters another reader's argument by taunting him? Seriously.

    the othe reader did not have much of an argument to begin with so he deserved the taunting
  • 0 Hide
    hunter315 , June 2, 2009 3:53 AM
    A performance per watt graph would have been nice especially as this was an article comparing lower powered processors as most of us dont run ours at full load for extended periods of time.
  • 0 Hide
    buzznut , June 2, 2009 3:56 AM
    Wow! I am waintin til the price comes down on the 905e, then I'm gettin one. For htpc build, It looks mighty tempting.
  • 2 Hide
    Anonymous , June 2, 2009 3:59 AM
    All this like many other toms articles show me there is not much difference between closely released proximity hardware!
  • 0 Hide
    cangelini , June 2, 2009 4:07 AM
    WoooooooooooooAll this like many other toms articles show me there is not much difference between closely released proximity hardware!


    When a release is incremental and evolutionary in nature, that's a pretty safe bet. There's no use in us embellishing the differences for theatrical effect now, is there?
  • 3 Hide
    Anonymous , June 2, 2009 5:12 AM
    @BillyBob: IronRyan posts an equally pointless pro-Intel fanboy comment everytime any article is posted, I couldn't take the waste of LCD screen space any longer, somebody had to say something.
  • 1 Hide
    MAD4AMD , June 2, 2009 5:47 AM
    Hit me with something Intel! And hit me with good/cheep or you may lose mainstream very quickly...
  • 7 Hide
    ohim , June 2, 2009 6:41 AM
    Is is me or iTunes shouldn`t be used as a benchmark since it`s beeing developed by apple wich uses only Intel CPU`s, and lame audio encoding ... i mean look at the other 2 multimedia programs used and look at those 2.
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