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AMD FX: Energy Efficiency Compared To Eight Other CPUs

Testing The Efficiency Of AMD's Bulldozer

Utilizing power efficiently isn't just a fringe message from environmentalists any more; it's a more mainstream concern, even from enthusiasts who are tired of pushing tons of air through their systems just to keep 300 W graphics cards stable. Processor vendors are on-board, too. AMD and Intel both preach the message of doing more with less power (generally whenever it's most convenient).

The message is a good one, though. Multiply out millions of platforms around the world and a few watts shaved off of each has a significant impact on the global energy demand. It's a matter of common sense: draw as much power required for the task at hand, but as little as possible when the performance (or energy use) isn't necessary.

In that regard, how do AMD's latest FX processors fare in the energy efficiency department?

Before it was FX, AMD's top-end desktop family was referred to as its code-name, Zambezi. What we discovered in AMD Bulldozer Review: FX-8150 Gets Tested was that AMD was not able to close the gap between its own best effort and Intel's almost year-old Sandy Bridge architecture.

It didn't help that launch pricing on the new FX chips made them more expensive than competing Intel-based products that are generally faster. Worse still, what can only be interpreted as very limited supply is currently inflating the cost of AMD's existing line-up. Now, we're seeing FX-8150s selling for $280 at the top-end and -4100s going for $130 at the bottom.

What Does Efficiency Mean, Anyway?

AMD isn't hopeless in its first generation of the Bulldozer architecture, though. The company's architects continually talk about maximizing what their hardware can do per watt of power consumption. Much effort was put into shutting down logic when it's not in use, and optimizing for efficiency. If the FX processors can achieve what its designers say (and what benchmarks have a difficult time showing when you look at performance on its own), then it's just a matter of finding the right price point for these CPUs.

To use an old car analogy, we're looking to measure the MPG rating of this processor at a given speed.

Low energy consumption on its own doesn't directly translate to high efficiency. Especially in today's world of single- and multi-threaded applications, it's important to take different workloads into account. We'd argue that no desktop machine runs at full throttle 24x7, making idle behavior incredibly important, too. We'd also go so far to say that big power consumption at full load is acceptable if a platform can get its task completed faster and drop back to idle (with its corresponding lower power use) yet again.

Benchmarks: Intel Sandy Bridge

Intel earned some well-deserved praise over the past few years for the efficiency of its Core processors and, even more so, the Sandy Bridge architecture (second-gen Core i3/i5/i7). In other words, systems based on those CPUs consume very little power at idle, and are also relatively energy-efficient under load.

We've already seen the performance numbers and know how that story ends. The question now is: how well does AMD handle efficiency with its new desktop flagship? Did the company's efforts to share certain on-die resources pay off with better over utilization of a nearly 2 billion-transistor design? Today we're comparing Zambezi to AMD's own Phenom II X4 and X6 products, along with comparable CPUs from Intel. How does AMD's top-end 125 W FX-8150 size up to its most potent competition, Intel's 95 W Core i5-2500K, in the efficiency department?

  • compton
    The low idle and load power consumption numbers of the SB K series are why I love them so much. Less power = less heat and noise, and SB is certainly worth it for me. BD, on the other hand, is just a strange bird. Someone out there could probably find a way to leverage it successfully, and that one person is going to be very happy. Maybe Bulldozer makes a lot more sense in its server configurations -- but I really wish AMD had just given the Phenom II a slight dust-off and die shrink. Everyone was pulling for AMD to do something great with BD, and the efficiency results are just abysmal. If you got great performance, but dis-proportionally high power consumption, that would be okay as well. With BD, you get the worst of both world, and not much of a saving grace. Perhaps Trinity will do something with this albatross that is BD and make it respectable, because the efficiency comparison is embarrasing.
    Reply
  • de5_Roy
    thank you tom's. this kind of article (performance-efficiency analysis) is one of my favorites. i've been waiting eagerly for an article like this from reviewer sites, tom's beat everyone else. :D
    the benchmarks with real world softwares(and not some specialized highly threaded synthetic benchmark that gives biased results) are the ones that matter to me. i use some of the softwares occassionally (blender), some more frequently (winrar, 7zip, lame encoder) and this article helped me a lot when i choose my next pc.
    did you guys see the ridiculous tdp number on cpu-z screenshot of fx8150? 223 w what the !@#$. i wonder which one got it wrong, amd or cpu-z.
    amd-fans-in-denial can argue as much as they want, but the reality didn't change. the efficiency numbers pretty much mirrored the bd review - bd isnt power efficient. even the ph ii 980 - the most power hungry of phenoms is more power efficient than fx 8150. and people who don't care about power consumption should care about the cooling and maintenance bd would need along with a power hungry high performance gfx card. imagine running an air-cooled fx 8150 @ 4.7 ghz with nvidia gtx 580 or radeon hd 6990.
    i can use any kind of acronyms like 'lol' or 'lmao' on bd's laughable power efficiency(even lynnfield beat it!) and performance but i am really sad and disappointed.
    if amd can't compete with intel, intel will keep selling their cpu at a high(and higher) price - avg users like me will be the loser.
    Reply
  • tacoslave
    everytime i read a BD article i die a little inside. Plus what we all knew would happen already started Intel already raised the K series prices a couple bucks.
    Reply
  • compton
    Geez, the 2700K is creeping up on $400. Thanks a lot AMD. You're off my Christmas list.
    Reply
  • dragonsqrrl
    comptonGeez, the 2700K is creeping up on $400. Thanks a lot AMD. You're off my Christmas list.Ya, the MSRP is $332, but the price on newegg is $370. Even for a brand new processor that's a huge premium over MSRP. It'll stabilize to the $330 price range eventually, but this initial price hike is no doubt related to the Bulldozer launch.
    Reply
  • de5_Roy
    @compton: phenom might get a die shrink with the llano upgrade. according to the latest trinity leak, llano's new 'husky' core will feature a phenom ii class cpu with amd 6xxx class gpu. this is just a rumor though.
    Reply
  • soccerdocks
    Thank you very much for including Matlab in the benchmarks. Its a really informative benchmark for those in engineering.
    Reply
  • "Everyone was pulling for AMD to do something great with BD, and the efficiency results are just abysmal."

    Not really, for the most time everyone was aware that BD was not going to be a SB killer, AMD themselves had hinted at it, then their PR department (propaganda office I would say) started pumping up the hype.

    Reply
  • amk-aka-Phantom
    And this is exactly why AMD fanboys should STFU about Bulldozer being an "excellent server CPU". You don't want high power consumption on a server.
    Reply
  • amk-aka-Phantom
    dragonsqrrlYa, the MSRP is $332, but the price on newegg is $370. Even for a brand new processor that's a huge premium over MSRP. It'll stabilize to the $330 price range eventually, but this initial price hike is no doubt related to the Bulldozer launch.
    2700K is BS... 100MHz extra is definitely not worth it. 2600K and 2500K remain best bang for buck right now.
    Reply