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Power Consumption

With Vishera, AMD was in a difficult position: it had to drive performance up without blowing through its 125W TDP. As the Piledriver cores were designed to do just that, Vishera benefitted. Remember that Piledriver was predominantly built to take this new architecture into mobile. I went through the details of what makes Piledriver different from its predecessor (Bulldozer) but at as far as power consumption is concerned, AMD moved to a different type of flip-flop in Piledriver that increased complexity on the design/timing end but decreased active power considerably. Basically, it made more work for AMD but resulted in a more power efficient chip without moving to a dramatically different architecture or new process node.

In mobile, AMD used these power saving gains to put Piledriver in mobile APUs, a place where Bulldozer never went. We saw this with Trinity, and surprisingly enough it managed to outperform the previous Llano generation APUs while improving battery life. On desktops however, AMD used the power savings offered by Piledriver to drive clock speeds up, thus increasing performance, without increasing power consumption. Since peak power didn't go up, overall power efficiency actually improves with Vishera over Zambezi. The chart below illustrates total system power consumption while running both passes of the x264 HD (5.0.1) benchmark to illustrate my point:

In the first pass Vishera actually draws a little less power, but once we get to the heavier second encode pass the two curves are mostly indistinguishable (Vishera still drops below Zambezi regularly). Vishera uses its extra frequency and IPC tweaks to complete the task sooner, and drive down to idle power levels, thus saving energy overall. The picture doesn't look as good though if we toss Ivy Bridge into the mix. Intel's 77W Core i5 3570K is targeted by AMD as the FX-8350's natural competitor. The 8350 is priced lower and actually outperforms the 3570K in this test, but it draws significantly more power:

The platforms aren't entirely comparable, but Intel maintains a huge power advantage over AMD. With the move to 22nm, Intel dropped power consumption over an already more power efficient Sandy Bridge CPU at 32nm. While Intel drove power consumption lower, AMD kept it constant and drove performance higher. Even if we look at the FX-8320 and toss Sandy Bridge into the mix, the situation doesn't change dramatically:

Sandy Bridge obviously consumes more than Ivy Bridge, but the gap between a Vishera and any of the two Intel platforms is significant. As I mentioned earlier however, this particular test runs quicker on Vishera however the test would have to be much longer in order to really give AMD the overall efficiency advantage.

If we look at average power over the course of the two x264 encode passes, the results back up what we've seen above:

Power Consumption - Load (x264 HD 5.0.1)

As more client PCs move towards smaller form factors, power consumption may become just as important as the single threaded performance gap. For those building in large cases this shouldn't be a problem, but for small form factor systems you'll want to go Ivy Bridge.

Note that idle power consumption can be competitive, but will obviously vary depending on the motherboard used (the Crosshair Formula V is hardly the lowest power AM3+ board available):

Power Consumption - Idle

3D Gaming Performance Projected Performance: Can AMD Catch up with Intel?
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  • Brainling - Wednesday, October 24, 2012 - link

    Translation: I am either paid by AMD, or a total fanboi, and these benchmarks did not say what I want them to say. So I am going to come on here and plug a different reviewers website, that is known to be AMD biased, and tell everyone how unbias they are and how their conclusions are the right ones, because they agree with my world view. Reply
  • yumeyao - Wednesday, October 24, 2012 - link

    I suggest stopping using x264 HD benchmark and looking for another test case.

    Let's look at what x264 HD benchmark does:

    Source film:
    MPEG-2!!! 6931kbps on avg, with a maximum bitrate of 12xxxkbps!!!
    You guys know that MPEG-2 is DVD standard...... DVD has a resolution of 480p(720x480 for wide-screen), but for FullHD it's 1920x1080, 6 times pixels as DVD has! And dvd has a ~5000kbps bitrate on avg, so what quality of the source film could we expect??

    And then let's look at its output:
    OMFG! 8000kbps!! h264!!!! I'd say for such a source, 2000kbps is fairly enough for an h264 output....

    So do you guys think such a test could ultimates a cpu's calculating potentials?

    I suggest finding any ts/BD-ISO source, and use proper options on x264 (basically you can directly use --preset xxx), then use it as a reference...
    Reply
  • Brainling - Wednesday, October 24, 2012 - link

    It's 125TDP part that gets consistently blown away by the 95 TDP Ivy Bridge, which has more transistors and a smaller more modern node process....and at the high end, it's really not that much cheaper than an Ivy Bridge i5.

    *sigh* Oh AMD...how the mighty have fallen. Can the real AMD, the one that gave us Thunderbird and Athlon64, please stand up?
    Reply
  • redwarrior - Wednesday, October 24, 2012 - link

    To the Intel fanatics whose bottom-line is" My car's better than your car, my car's better than yours. What infantile sensibilities . The computer is a tool. A multifaceted tool that has 1001 purposes. The AMD technology meets the needs of 99.99% of computer users with a better bang for the buck. Only a one-dimensional person can say otherwise. Myopic gamers need to open their eyes and see there is a bigger world out there. Reply
  • CeriseCogburn - Tuesday, October 30, 2012 - link

    Here we go again, the activist on another preaching rampage, with his attack on Intel cpu owners.... nice little OWS protest against the rich Intel people...

    You wouldn't mind then if I said I can't stand you cheap, broke, ghetto amd dirty little rascals who can't pay for themselves let alone the education they need to properly use a computer.
    Not to mention your ignorance in supporting a losing, technologically backwards second tier set of idiots wasting monetary resources that could be spent on something good for the world instead of on foolish amd misadventures that pay interest on amd's debt and not much else.
    You ought to support the company that pays a LIVING WAGE, instead of the one firing their employees, axing them over and over again.

    Thanks for not being capable of properly acquiring and using a computer.
    Reply
  • 7beauties - Wednesday, October 24, 2012 - link

    I've rooted for AMD against Intel before I built my first PC with the 700Mhz Athlon in 2000. AMD stole Intel's thunder to much acclaim. For a while AMD and Intel dueled for supremacy, exchanging leads, much like the tit for tat between Radeon and Geforce GPU's are engaged in. AMD's scrappy fight spurred Intel's clock to speed up its ticks and tocks, and the computing world benefited from this. It would be bad for all of us if AMD goes out of business. I root for the underdog, for David against Goliath, but David is lying on the ground and boasting of winning. It was embarrassing when the Phenom was so unphenomenal. Then AMD heralded the Bulldozer. Bulldoze what? The empty hype makes the truth more painful. Intel plans to integrate the South Bridge onto Haswell's die, and folks, AMD will lose teeth and get bloodied. I'm growing weary of being a sort of Cubs fan. Reply
  • CeriseCogburn - Tuesday, October 30, 2012 - link

    You simpletons all have the same hate filled idiot theory - so let me ask you - since amd has competition, WHY DO THEY SUCK SO BADLY ?

    Somehow you idiots claim, that if amd wasn't around, intel would suck. "Amd has made intel great"

    Well, wait a minute - Intel is around, it's great, AND AMD SUCKS.

    Take a moment, look in the mirror, think about it.... then let me know how red you turned... if not at all, contraception from here on out is a must.

    How are you people so stupid ? How is it possible ?
    Reply
  • Ukdude21 - Thursday, August 15, 2013 - link

    You the biggest idiot on this website. I have read many comments on this website but yours are the most idiotic intel fanboy stained comments ever. Reply
  • halbhh2 - Thursday, October 25, 2012 - link

    If power use is important to you, you should know that different reviews give different results for the power use vs competing intel chips.

    A couple of sites even have equal or lower idle power draw for the 8350 vs i7 3770.

    Trying to figure out why, one variable is the motherboard. Is the Crosshair V a power hog?

    I also looked at yearly cost in electrical use for my own useage.

    The only thing I do that pegs multiple cores at 100% is chess analysis. In Deep Fritz the 8350 is close in performance to the i7 3770.

    I do chess analysis about 1-5 hours a week on average, perhaps 200 hours per year.

    The math is very simple. Power costs 16 cents per kilowatt hour. Peak power useage would cost an extra $3/year roughly vs an intel rig for me. Since I'd use a more power efficient motherboard than the Asus Crosshair, idle power is reasonable. I standby a lot when not using also.

    An 8350 would cost me in the range of $4-$8 more per year in power bills vs an i7 3770 (it's competitor for chess analysis).
    Reply
  • CeriseCogburn - Tuesday, October 30, 2012 - link

    So go ahead and destroy the earth, see if any humans care. Reply

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