• What
    is this?

    You've landed on the AMD Portal on AnandTech. This section is sponsored by AMD. It features a collection of all of our independent AMD content, as well as Tweets & News from AMD directly. AMD will also be running a couple of huge giveaways here so check back for those.

    PRESENTED BY

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?
POST A COMMENT

229 Comments

View All Comments

  • 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
  • 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
  • sleekz - Thursday, May 02, 2013 - link

    Priced cheaply, but they don't match price/performance wise. Price is not a valid argument against intel. Reply
  • Abdussamad - Monday, August 12, 2013 - link

    Do the math on electricity consumption and you find it is not priced decently at all. Let's say you run a system with an idle FX 8350 for 8 hours a day everyday for 5 years and electricity costs you $0.16 per kwh:

    (( 8 hours * (74.2 - 57.5) * 365 days * 5 years ) / 1000) * 0.16 = $39

    (74.2 - 57.5 is the difference in idle power consumption between an fx-8350 and i5-3570)

    So add $40 to the price of the FX 8350 before you do a comparison. More if you run your system 24/7.
    Reply
  • lostinspacex - Wednesday, November 13, 2013 - link

    duuude its 40 dollars in 5 years, you spend more going to a restaurant once , and u are multiplying watts with kilowatts xD, basic math mistake Reply
  • chekk42 - Wednesday, November 13, 2013 - link

    Look closer. The math is correct. However, yes, $40 over 5 years is not really a concern. Reply
  • ninza228248 - Monday, April 14, 2014 - link

    After 5 years add $40 to AMD and you will get mind blowing processor compared to Intel Core i5-3570 or any intel processor after 5 years in that price bracket... Reply

Log in

Don't have an account? Sign up now