DDR/NetBurst Memory Bandwidth and Latency

One of the most talked-about AMD advantages of the last couple of years has been their on-processor memory controller. This has allowed, according to popular theories, the Athlon64 to significantly outperform Intel NetBurst processors. The fact is NetBurst DDR2 bandwidth has recently been similar or wider in bandwidth than Athlon64 - even when the DDR is overclocked. You can see this clearly when we compare Buffered and Unbuffered Bandwidth of a NetBurst 3.46EE to an AMD 4800+ x2(2.4GHz, 2x1MB Cache) running DDR400 2-2-2 and running overclocked memory at DDR533 3-3-3.

The green bars represent DDR memory performance, while the beige to red are increasing DDR2 speed on NetBurst. Light green represents DDR400 2-2-2 while Dark Green is overclocked memory at the same CPU speed, DDR533 at 3-3-3.

Standard (Buffered) Memory Test


In buffered performance, Fast DDR400 is only faster than DDR2-400 and slower than DDR2-533, 667 and 800. Overclocked memory at DDR533 3-3-3 is faster than any of the DDR2 bandwidths on NetBurst.

The Sandra Unbuffered Memory Test, which turns off features that tend to artificially boost performance, is generally a better measure of how memory will behave comparatively in gaming. The same green for DDR applies here.

Unbuffered Memory Test


Without Buffering, DDR400 has the smallest bandwidth of tested memory speeds and timings. Even overclocking to DDR533 allows the DDR to barely beat DDR2-400. DDR2-533, 667, and 800 all have greater Unbuffered bandwidth than the DDR overclocked to 533. NetBurst DDR2 memory bandwidth is generally wider than the bandwidth supplied by DDR memory on Athlon64. Despite the wider bandwidth, the deep pipelines and other inefficiencies in the NetBurst design did not allow the NetBurst processors to outperform Athlon64. Keep this in mind later, when we look at AM2 and Core 2 Duo Memory Bandwidth.

Latency

The other area where AMD has had an advantage over NetBurst DDR2 performance is memory latency, the result of the on-processor memory controller. Comparison of the AMD DDR Memory controller and the Intel DDR2 Memory controller in the Intel chipset shows AMD DDR with latency about 35% lower than Intel NetBurst in Science Mark 2.0.

Memory Latency Comparison - DDR & NetBurst


While memory bandwidth was very similar between AMD and NetBurst, the deep pipes of the NetBurst design still behaved as if they were bandwidth starved. On the other hand the AMD architecture made use of the bandwidth available and the much lower latency to outperform NetBurst across the board.

Index AM2/Core 2 Duo Latency and Memory Bandwidth
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  • drebo - Tuesday, July 25, 2006 - link

    Excuse me, but the E6400 wasn't even IN the benchmarks Anandtech ran, but by extrapolation(considering the E6700 did not beat out the 5000+ by a large margin), it cannot perform better than the 5000+.

    And, in the majority of benchmarks, such as the ones http://www.anandtech.com/cpuchipsets/showdoc.aspx?...">here, which are benchmarks that have traditionally favored Intel processors in the past, the AMD chips do not fall as you paint them. They fall as I have painted them. The 4200+ outperforms the E6300 in ALL of them...and costs LESS. The 5000+ matches performance in 2/3 of them with the E6600. And costs LESS.

    Sorry, but this isn't about which company is better or provides a better product. This is about which company provides a better product at a better price. We all know the X6800 is the best desktop processor available. NO ONE is disputing that. The dispute is that review sites are proclaiming that the Core 2 Duos are god's gift to Intel and that Athlon64s are completely worthless now, which is NOT the case.

    In the $1k processor range, sure, Core 2 Duo is the king...but AMD doesn't have a processor in that range anymore. There is no competition to the X6800 anymore. At every other price point, however, the Athlon64 X2 processors are extremely competative.
    Reply
  • coldpower27 - Tuesday, July 25, 2006 - link

    Take a look at these benchmarks show the E6400 in them, and for the most part it beats out the 4600+

    http://xbitlabs.com/articles/cpu/display/core2duo-...">http://xbitlabs.com/articles/cpu/display/core2duo-...
    Reply
  • coldpower27 - Tuesday, July 25, 2006 - link

    Oh please, you looked at 1 page of benchmark to make your conclusion??

    Did you just look at 3D Rendering to draq your conclusions?

    What about the encoding and gaming performance? Did you look at those?
    Reply
  • IntelUser2000 - Wednesday, July 26, 2006 - link

    quote:

    Oh please, you looked at 1 page of benchmark to make your conclusion??

    Did you just look at 3D Rendering to draq your conclusions?

    What about the encoding and gaming performance? Did you look at those?


    It is obvious you haven't seen both of my posts fully. Please do. Core 2 Duo outperforms.

    This is type of performance increase people would have been crazy about, but somehow its different. Maybe its conspiracy to kill Intel??
    Reply
  • coldpower27 - Wednesday, July 26, 2006 - link

    IntelUser2000.

    Chill. I am reply to drebo in this reply not you. Anandtech comment posting system is just strange.
    Reply
  • IntelUser2000 - Tuesday, July 25, 2006 - link

    quote:

    And, in the majority of benchmarks, such as the ones here, which are benchmarks that have traditionally favored Intel processors in the past, the AMD chips do not fall as you paint them. They fall as I have painted them. The 4200+ outperforms the E6300 in ALL of them...and costs LESS. The 5000+ matches performance in 2/3 of them with the E6600. And costs LESS.


    Please stop being an idiot. If you see Anandtech's benchmarks you can clearly see that E6600 is FASTER overall than FX-62. That's why the saying of $316 FX-62 came about.


    For those that are in denial about the FACT that E6600 with $316 price beats FX-62

    Application Performance using SYSMark 2004 SE
    Average performance: 18.6% in favor of E6600

    Application Performance using PC WorldBench 5
    1.4% advantage of Core 2 Duo E6600

    Application Performance using Winstone 2004
    2.9% advantage of FX-62, E6600 equal or faster than 5000+

    3D Rendering Performance using 3dsmax 7 & CineBench 9.5
    2.7% advantage of FX-62, E6600 faster than 5000+

    Encoding Performance using DivX 6.1, WME9, Quicktime (H.264) & iTunes
    6.0% advantage of E6600

    Overall Gaming Performance
    11.6% advantage of E6600


    Total Performance increase of E6600 over Athlon FX-62
    Core 2 Duo E6600 is 9.9% faster overall than Athlon FX-62!!
    Reply
  • IntelUser2000 - Tuesday, July 25, 2006 - link

    Normally, the kind of performance advantage E6600 gives over the FX-62 would have meant people would have flocked over to E6600 even if it was previous high-end mainstream price for Intel processors, which is $637.

    Stop spreading false info people(anti-intel, and i am saying lightly), cause not only your beloved Athlon 64 X2 5000+ slower than E6600, so is AMD's top end offering, the FX-62!!!

    I remember people saying Core Duo was worth it(yes the Yonah). Based on the logic people are spreading for Core 2 Duo argument, Core Duo wasn't worth it at all. $637 for the top end Core Duo(Yonah), and being barely faster per clock than FX-62 when clocked outrageously high(30% over stock, while FX-62 is at stock), plus expensive motherboards that are hard to find.

    If Core Duo was worth it at all, well... Core 2 Duo is like a dream.
    Reply
  • Accord99 - Tuesday, July 25, 2006 - link

    And the E6300 does better in other tests, such as the Sysmark, video encoding and games. And the E6600 doesn't compete with the 5000+, it competes with the FX-64. Reply
  • drebo - Tuesday, July 25, 2006 - link

    I don't know what benchmarks you're looking at, but they sure as hell aren't posted on any review site I've ever seen.

    I never expected my opinion that AMD is not dead and Intel is not master of all to be popular, but I atleast expected some constructive responses. Yes, Intel has the best performing processor. We know this. No one cares. I'm sure AMD could spin a 3.2ghz FX-70 or something and sell it for $2000. But why bother, for 2% of the population to use? The vast majority of computer users are looking for performance-per-dollar, and there is no difference between Athlon64 X2 processors and Core 2 Duo processors in that ratio...except, of course, motherboard...which tends to cost near to twice as much on the Core 2 Duo side.

    Yes, Intel released a competative platform. We're all very happy with them, and once they're available, it'll be great...but they're hardly a nail in the coffin for AMD. AMD still holds the superior chips for single-core, and performance-per-dollar is just as good as Core 2 Duo, and I can tell you from personal experience, that's what matters.

    Go go objectivity!
    Reply
  • Accord99 - Tuesday, July 25, 2006 - link

    I'm just looking at all the Anandtech benchmarks. It's quite clear the E6300 is faster than the 4200+ overall, while the E6600 is faster than the FX-62 overall.

    So performance/dollar is higher for Conroe, the current motherboards are more expensive but that can be made up from purchasing less high-end memory. And Conroe uses less power.
    Reply

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