More Cores - The Ticket to Power Efficiency?

When Intel started on its quest for greater power efficiency we heard much about how the ticket would be more cores and multi-threaded applications. Instead of focusing on increasing clock speed Intel turned to the world and admitted that its gigahertz race was foolish, and that the next decade of performance improvements would come from increasing the number of cores per processor, not clock speed.

Back in 2005 Intel displayed the following chart, plotting a new curve for performance made possible mostly by the move to multi-core processors:

But at the same time, just as Intel had learned from the Pentium 4 family, an endless pursuit of performance (whether in the form of higher clock speed or more cores) will simply run us into another power wall. So as we were hearing about the performance improvements the multi-core era would bring us, we were also being told that Intel would not only improve the performance vector, but performance-per-watt as well. In fact, Apple cited Intel's focus on performance-per-watt as the driving factor in its adoption of Intel CPUs:

The introduction of Intel's Core microarchitecture proved one very important point: individual core improvements, as well as simply adding more cores, will both be necessary to drive better performance per watt in future microprocessors.

Looking at Intel's own numbers, the move from one to two cores improved performance per watt on the mobile side by around 50% while the move from NetBurst to Core on the desktop side increased performance per watt by a magnitude of 5x.

But is Kentsfield nothing more than a cleverly masked return to an older Intel? An Intel that used its manufacturing abilities to out-market AMD but left us with much higher power consumption than we wanted (and needed) to have? With Kentsfield we have two Conroes on a single chip, with no tweaks to the cores and very inefficient power management between the two die. Is this really no different than when Intel simply pushed out CPUs with higher clock frequencies, without addressing efficiency, to really turn up the heat on AMD?

Intel has said that it is committed to improving performance and performance per watt, but it was time to test that commitment with Kentsfield.

To put Intel's marketing and IDF presentations to the test we took six of our multithreaded benchmarks and ran them on a handful of configurations. Instead of just measuring performance, we also looked at average power usage during the benchmark and obviously, performance per watt. While all six benchmarks benefit from dual core CPUs, only four of them show a gain when using a quad core CPU, which should be useful in illustrating a very important correlation between number of threads and performance per watt.

Using a Quad Core System Performance per Watt Comparison
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  • Sharky974 - Friday, November 3, 2006 - link

    Dudes, I remember reading, with detailed benchmarks from a site that specialized in HDD's, that raid array's for speed are COMPLETELY AND UNEQUIVICABLY USELESS.

    It bugs me too, because then as now, people just refuse to accept that fact, even with benchmarks proving it over and over staring them right in the face. RAID DOES NOT SPEED UP YOUR SYSTEM. PERIOD.

    If you want to use it for auto backup otoh, fine..
  • cjb110 - Thursday, November 2, 2006 - link

    One question I would like answered, would a quad core help with the gaming and background task usage? (i.e. IM, P2P etc etc) Is Windows intellegent enough to use those cores properly?

    Reason I ask is I'm planning to go from a 2 pc setup (1 gaming, 1 background tasks) to a single setup, and wondering if quad would be an even better solution for me?
  • Sunrise089 - Thursday, November 2, 2006 - link

    Probably not. While this sounds like a good idea, the main benefit in going dual-core is offloading 100% of those background tasts to the second core, so the game gets one core all to itself. Moving from two to four does almost nothing because there isn't anything else to unload. Now, in the future there will be more titles that will use 2 cores, so 4 core chips have their uses, but by then most readers of this site will have upgraded again anyways.
  • JarredWalton - Thursday, November 2, 2006 - link

    Depends on the background tasks. If you're running something in the background like media encoding, which can already easily use two cores, I would expect quad core to do better. If you're running BitTorrent plus media encoding plus a TV recording application, then I would expect even more benefit if you try to game. Of course, if you're doing all that, you better have a nice HDD configuration as well. RAID 0 with NCQ enabled should suffice.
  • Sunrise089 - Thursday, November 2, 2006 - link

    Ok, sure, but when most people ask this question they are talking about a game plus IM and anti-virus and maybe a Firefox window. Not all that many people play fullscreen games while encoding files and bittorrenting.
  • JarredWalton - Thursday, November 2, 2006 - link

    Right, in which case there's little difference, at least right now. When games start coming out that can use multiple cores (not just 2 or even 4), then it could become a lot more important. For now, dual cores is plenty for 99% of people.
  • shabby - Thursday, November 2, 2006 - link

    I love it how steve jobs is pimping the intel chip now, before his ppc chips were oh so much faster then intel chips. What a two faced whore...
  • Donegrim - Thursday, November 2, 2006 - link

    But before his ppc chips WERE more powerful than Intel ones. Before the core architecture came into being. Now the core is faster than the ppc, so he is using them. Makes sense really, I'm sure I'd do the same.
  • Griswold - Thursday, November 2, 2006 - link

    Nah, he was cursing the whole x86 architecture. By your logic, he could have went with AMD while Intel was touting their netburst furnaces.
  • peternelson - Thursday, November 2, 2006 - link

    "4x4 is an entirely new platform using Socket-1207 (not AM2) CPUs. As much as AMD wants 4x4 to succeed, what we're really waiting for is Barcelona. "

    HAS AMD ANNOUNCED CLEARLY that 4x4 will be only 1207 and NOT AVAILABLE for AM2?

    In earlier announcements it looked like 4x4 would be AM2 (hence speculation about how it could dual socket without extra hypertransport links). PLEASE STATE IF AMD HAVE MADE AN UNAMBIGUOUS STATEMENT OR CLARIFICATION TO THIS EFFECT. Note 4x4 and the acceleration coprocessor tech are two different technologies and might be confused if they are in the same conference/press release or anandtech article.

    In any case AMD promised 4x4 during 2006, so we will know the answers real soon ;-)

    I think 4x4 will not be nice just for two dualcores, but for have TWO QUADCORES. Now depending on if those quadcores can be AM2 or 1207 or available for either, that will alter the price/performance of AMD's offering.

    However I am looking forward to an 8 core system from AMD.

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