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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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  • g101 - Wednesday, November 21, 2012 - link

    Oh look, it's the highly ignorant fool CeriseCogburn...

    You make demonstrably false statements on every single AMD article and merely provide further proof of your ignorance. Honestly, if you're unable to find anything better to do than post idiotic comments on every anadtech article, I have a suggestion: EDUCATE YOURSELF, LITTLE DIPSHIT.
    Reply
  • Desolator2B - Wednesday, November 21, 2012 - link

    Dude, seriously? Did you know the current world record for overclocking is held on an AMD processor? AMD is incredible when overclocking, especially super cooling, yes it may be a bit slower than Intel, but damn you can't beat AMDs price.

    You're a bit of an idiot mate.
    Reply
  • JrPgFaN83 - Wednesday, May 14, 2014 - link

    i couldn't have said it better myself mate. This response made the read worth it. Reply
  • vench - Friday, November 23, 2012 - link

    think about this..
    which one is better an eight unlock cores as AMD called it.
    or 4 cores with hyperthreading technology?

    4 cores with hyperthreading it will act like an eight cores because single core will act like two cores as claimed by intel but bear in mind there would be a mathematical complex going on behind intels hyperthreading. but WHAT if you unlock this thing so it would go freely to eight cores as claim by AMD?

    THAT IS THE REASON WHY AMD HOLDS THE WORLD RECORD FOR OVERCLOCKING BECAUSE THEY MANAGED TO UNLOCK THIS THING.
    IF INTEL WILL PRODUCE 8 CORES CPU..THEN AMD WILL MAKE 16 CORES..AND THEN AMD STILL WIL BE THE WINNER FOR WORLD RECORD..

    ON THIS POINT OF VIEW JUST BE OPEN MINDED.
    DO NOT ACT LIKE YOU REALLY SICK WHEN ITS NOT BECAUSE YOU WOULD MAKE YOURSELF LIKE TWICE MORON AND TWICE IDIOT.
    JUST TAKE AN ADVICE FROM G101. EDUCATE YOURSELF.

    I USED TO BE AN INTEL USER.. BUT WHEN I'M BEGINNING TO UNDERSTAND THIS TREND..I WOULD LOVE AMD AS THEY LOVE CONSUMER'S POCKET (AGAIN- BE OPEN MIND. ITS MY OPINION)
    Reply
  • sleekz - Thursday, May 02, 2013 - link

    CAPS. The world overclocking record is meaningless. You can't compare clock speed across brands and AMD cores are half-cores. They still can't compete with intel and the circuit size is several years behind, which is why they consume so much power. AMD has given up in the enthusiast CPU market, and is losing money. Reply
  • JrPgFaN83 - Wednesday, May 14, 2014 - link

    AMEN! Reply
  • Mombasa69 - Thursday, March 14, 2013 - link

    My AMD Vishera 8350 blows my ghay i7 3770k out the water and was HALF THE PRICE, says it all really. Reply
  • Etnos - Saturday, April 20, 2013 - link

    I hardly think you own intel shares so the fact you care so much is pretty sad.

    very sad.
    Reply
  • Idiot10 - Tuesday, May 07, 2013 - link

    Here comes the 2500K-loving Intel mercenary know-it-all-about-processors again, and yet he cannot sleep to know that there are chips out there who can outperform his 2500K. SOB!!!! Reply
  • Idiot10 - Tuesday, May 07, 2013 - link

    Here comes Mr. ChariseHogburn again. the all-knowing Intel mercenary processor expert, who thinks nothing can beat his beloved 2500K. SOB!!!! Reply

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