AM2/Core 2 Duo Latency and Memory Bandwidth

The introduction of AM2 merely increased the AMD latency advantage. AM2 latency was slightly lower than DDR latency on AMD.

Memory Latency Comparison - Conroe & AM2

However, Core 2 Duo did what most believed was impossible in Latency. One of AMD's advantages is the on-processor memory controller, which Intel has avoided. It should not be possible to use a Memory Controller in the chipset on the motherboard instead and achieve lower latency. Intel developed read-ahead technologies that don't really break this rule, but to the system, in some situations, the Intel Core 2 Duo appears to have lower latency than AM2, and the memory controller functions as if it were lower latency.

Memory Bandwidth

The other part of the memory performance equation is memory bandwidth, and here you may be surprised, based on Conroe's performance lead, to see the changes Core 2 Duo has brought. Results are the average of ALU/FPU results on Sandra 2007 Standard (Buffered) memory performance test. We used the same memory on all three systems, and the fastest memory timings possible were used at each memory speed.


The results are not a mistake. In standard memory bandwidth, Core 2 Duo has lower memory bandwidth than either AM2 or Intel NetBurst. It is almost as if the tables have turned around. AMD had lower bandwidth with DDR than Intel NetBurst, and the Athlon64 outperformed Intel NetBurst. Now Conroe has the poorest Memory Bandwidth of any of the three processors, yet Conroe has a very large performance lead. It appears Conroe, with shallower pipes and an optimized read-ahead memory controller to lower apparent latency, makes best use of the memory bandwidth available.

Perhaps the most interesting statistics are that the huge increases in memory bandwidth brought by AM2 make almost no difference in AM2 performance compared to the earlier DDR-based Athlon64. With this perspective let's take a closer look at DDR2 memory performance on AM2 and Core 2 Duo. This will include as close to an apples-to-apples comparison of Core 2 Duo and AM2 as we can create.

DDR/NetBurst Memory Bandwidth and Latency Memory Test Configuration
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  • duploxxx - Thursday, July 27, 2006 - link

    please give us edit...

    powerconsumption is only less in 100% load.... when powermode kicks in the amd is much less consuming... how long do you think a system runs in powermode against full load....
    Reply
  • duploxxx - Thursday, July 27, 2006 - link

    wrong... the conroe gains from the memory speed the amd more thats a fact... the ones you are referring to are probably 4200 and 5000, well we can say that they perfrom better when using 533/667 because then they don't have the devider issue running the memory on 742 in stead of 800.

    so the performance/price ratio on those chips is better with 553/667
    Reply
  • zsdersw - Thursday, July 27, 2006 - link

    Conroe's performance isn't merely a function of memory bandwidth or memory speed. Reply
  • PeterR - Tuesday, July 25, 2006 - link

    If you could actually go out and BUY one ?

    Peter R.
    Reply
  • michal1980 - Tuesday, July 25, 2006 - link

    Wow. AMD fanboi's pulling out all the crap that the intel fanboi's have pulled in the past.


    wake up!. Right now, Intel core 2 duo is faster then AMD 64 right now.

    Its like video card fanboi's but worse, because the difference here is clear.

    If I was building a gaming rig this year, I would build with a core 2 duo.

    Just like a few months ago, it would be with an AMD 64.

    I go with what company is faster. I used both nvidia cards, and ati Cards. I use pentiums, and p2's, I used athlon xp's when you over clock them 50% ease and they were dirt cheap. I use a opty dual core right now because it was faster then the p4's. I use p-m lappys because of performance/battery life.

    If I was building a rig right now. I'd switch to an intel Core 2 duo. Why? because its faster. I could care less about who makes it.

    if apple comes out tommorow with a magic pc that runs all pc games run 20% faster, I'm buying an apple.
    Reply
  • Pirks - Tuesday, July 25, 2006 - link

    quote:

    if apple comes out tommorow with a magic pc that runs all pc games run 20% faster, I'm buying an apple
    I'd buy a iMac or Mac Pro right this second if it were running all PC games at all without rebooting between OS X and XP.
    Reply
  • yacoub - Tuesday, July 25, 2006 - link

    Two things:

    1 - I think I like the new font used in tables and charts.

    2 - In the SuperPi chart you say Lower is Better but then inverse the graph such that it is actually the line higher on the graph that is better. Unless the reader looks closely at the numbers, they could infer that the AMD chip wipes the floor with the Conroe.
    Reply
  • redbone75 - Tuesday, July 25, 2006 - link

    Seriously, though, here we have a completely new architecture from Intel, the same Intel that is this massive company with enormous resources and huge R&D departments, and these AMD fanboys are still all upset because Intel has not only achieved parity with but also exceded AMD in performance. Come to think of it, this is the exact same argument that AMD fans were using when preliminary benchmarks came out on Conroe. "It's not fair to compare Intel's new architecture to AMD's old one, because they have an advantage." Hey, you want some cheese with that wine? I'll tell you what: AMD enjoyed the performance lead for a while. Now, Intel is having a go at it and, with any luck, AMD will come out on top in the future, at least I really hope so. Why do I hope so? Do any of you think AMD would have lowered their processor prices so much if Conroe wasn't such a threat? Do you think Intel would have released Conroe at these prices if they didn't have to take back the crown from AMD? Hey, with the X2's we still get a great range of processors at much lower prices. Hell, even the Pentium D's are going to be attractive at lower prices. That makes me happy, not some benchmarks saying this processor is faster than that processor. And really, I don't know about you but I don't care about which processor wins memory latency benches, I only care about the end performance in applications I actually use. Reply
  • DigitalFreak - Tuesday, July 25, 2006 - link

    Amen, brother! Reply
  • TravelMug - Tuesday, July 25, 2006 - link

    As said by several people before - you are not testing latency but the prefetch abilites of the CPU. Same has been said about the original Conroe article, you don`t seem to listen though.

    "Everest from Lavalys shows latency improvements in the new CPU revisions, but it shows Latency more as we would expect in evaluating Conroe. For that reason, our detailed benchmarks for latency will use both Everest 1.51.195, which fully supports the Core 2 Duo processor, and ScienceMark 2.0."

    Really? That is a 2 years old version, there have been countless new version since then. Also, if that version "fully supports" the Core 2 Duo processor, how come this is what the developer says about the latest version 3.01?:

    http://www.lavalys.com/products/whatsnew.php?pid=3...">Support for Intel Core 2 "Conroe" and "Merom" processors
    Reply

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