Core 2 Duo (Conroe) launched about twelve days ago with a lot of fanfare. With the largest boost in real performance the industry has seen in almost a decade it is easy to understand the big splash Core 2 Duo has made in a very short time. AnandTech delivered an in-depth analysis of CPU performance in Intel's Core 2 Extreme & Core 2 Duo: The Empire Strikes Back. With so much new and exciting information about Conroe's performance, it is easy to assume that since Core 2 Duo uses DDR2, just like NetBurst, then memory performance must therefore be very similar to the DDR2-based Intel NetBurst architecture.

Actually, nothing could be further from the truth. While the chipsets still include 975X and the new P965 and the CPU is still Socket T, the shorter pipes, 4 MB unified cache, intelligent look-ahead, and more work per clock cycle all contribute to Conroe exhibiting very different DDR2 memory behavior. It would be easy to say that Core 2 Duo is more like the AMD AM2, launched May 23rd, which now supports DDR2 memory as well. That would be a stretch, however, since AM2 uses an efficient on-processor memory controller, and the launch review found Core 2 Duo faster at the same clock speed than the current AM2. This is another way of saying Conroe is capable of doing more work per cycle - something we had been saying for several years about Athlon64 compared to NetBurst,

The move by AMD from Socket 939 to Socket AM2 is pretty straightforward. The new AM2 processors will continue to be built using the same 90nm manufacturing process currently used for Athlon 64 processors until some time in early to mid-2007. AMD will then slowly roll-out their 65nm process from the bottom of the line to the top according to AMD road-maps. This could include memory controller enhancements and possibly more. Performance of AM2 only changed very slightly with the move to DDR2, generally in the range of 0% to 5%. The only substantive difference with AM2 is the move from DDR memory to official AMD DDR2 memory support.

Our AM2 launch reviews and the article First Look: AM2 DDR2 vs. 939 DDR Performance found that AM2 with DDR2-533 memory performed roughly the same as the older Socket 939 with fast DDR400 memory. Memory faster than DDR2-533, namely DDR2-667 and DDR2-800, brought slightly higher memory performance to AM2.

The Core 2 Duo introduction is quite different. Clock speed moved down and performance moved up. The top Core 2 Duo, the X6800, is almost 1GHz slower than the older top NetBurst chip and performs 35% to 45% faster. With the huge efficiency and performance increases comes different behavior with DDR2 memory.

With the world now united behind DDR2, it is time to take a closer look at how DDR2 behaves on both the new Intel Core 2 Duo and the AMD AM2 platforms. The performance of both new DDR2 platforms will also be compared to NetBurst DDR2 performance, since the DDR2 NetBurst Architecture has been around for a couple of years and is familiar. We specifically want to know the measured latency of each new platform, how they compare in memory bandwidth, and the scaling of both Core 2 Duo and AM2 as we increase memory speed to DDR2-1067 and beyond. With this information and tests of the same memory on each platform, we hope to be able to answer whether memory test results on Conroe, for instance, will tell us how the memory will perform on AM2.

In addition we have an apples-apples comparison of AM2 and Core 2 Duo running at 2.93GHz (11x266) using the same memory at the same timings and voltages with the same GPU, hard drive, and PSU. This allows a direct memory comparison at 2.93GHz at DDR2-1067. It also provides some very revealing performance results for Core 2 Duo and AM2 at the exact same speeds in the same configurations.

DDR/NetBurst Memory Bandwidth and Latency
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  • HSuke - Thursday, July 27, 2006 - link

    quote:

    This fact will make our memory testing much simpler, and we plan to perform all upcoming memory testing on the currently more flexible Core 2 Duo test platform. AM2 buyers can expect similar results with the same DDR2 memory on their AM2 motherboards.


    I hope this means that you're going to do the tests on the Core 2 Duo test platform IN ADDITION to your current platforms.

    I hope this does NOT mean that you're going to do the tests EXCLUSIVELY on the Core 2 Duo test platform.



    So are you going to stop doing memory tests with AMD processors? How scientific is that? If you go to page 7 and look at the performance charts, you'll see that memory speeds have a much greater impact (pertage-wise) on the AMD setup than the Core 2 Duo setup.

    Well, I'm quite surprised that memory even made a difference. But since that is true (according to your tests), shouldn't be testing on AM2 instead of Core 2 Duo processors in the future because the difference is more marked? If there wasn't any significant difference on an Intel system, but a significant difference on an AMD system, you'd probably suggest that memory doesn't make a difference, commiting a type 2 error.

    Now, I don't care about memory. I always buy whatever is on sale. But making that conclusion would just piss off so many memory enthusiasts and memory sellers. And aren't those guys the ones that would be reading this article?

    Think about it.
    Reply
  • Wesley Fink - Friday, July 28, 2006 - link

    As we explained in the article, AM2 currently does not support the DDR2-1067 speed, while the Intel chipset for Core 2 Duo DOES support 1067. Since most memory we test can reach 900 to 1067 or 1100 or greater the 1067 ratio is an advantage. Also the current AM2 memory controller does not support settings of 2 for Ras-to-Cas or tRef - AM2 only supports to 3. Core 2 Dupo supports faster timings of 2 at these settings. Since these lower settings are often usable in fast memory they can be very important.

    For these reasons, we will be using the Core 2 Duo platform for testing DDR2 memory, since we can test more of the options that are available and may be important on high-performance DDR2 memory. If and when AM2 upgrades their DDR2 memory controller we will reconsider testing on AM2.
    Reply
  • Kiijibari - Wednesday, July 26, 2006 - link

    Hi everybody,

    first of all I have to admit that this is the best Anandtech article for a long time. Everybody blamed me for being an AMD fanboy latley, however I do not have any problems to admit that Core2 is faster.

    If Intel would not have anything faster than AMD after 3 years of AMD lead, Intel would be best adwised to stop making CPUs and become an AMD chipset company ;-)

    I have one question left: Which BIOS version did you use with the AM2 board ?
    I recoginzed that DDR2 bandwidth scores increased quiet much compared to the initial tests. Now we have Sandra scores around 9.3 GB/s, however I remember that the initial ones were around 7.4 GB/s max.

    In conclusion I assume that there is some optimization going on, due to bios seetings.

    There was also a little test over at lostcircuits:
    http://www.lostcircuits.com/motherboard/foxconn_c5...">http://www.lostcircuits.com/motherboard/foxconn_c5...

    There the Asus board scored just ~7 GB/s, but a tested Foxconn board is again in the 9GB/s area.

    It maybe that the BIOSes are optimized for different kind of RAMs, too, as lostcircuit used OCZ memory, not Corsair.

    Anyways, I think the results are interesting enough to dig a little bit further ;-)

    Thanks again for the great review.

    regards

    Kiijibari

    Reply
  • Wesley Fink - Wednesday, July 26, 2006 - link

    P5W-DH Deluxe BIOS is 701, dated 7/08/2006. The Corsair memory used in this review can do 4-3-4-11 timings at DDR2-1067, where most high-end DDR2 can only reach 4-4-4 timings at that speed. Reply
  • Kiijibari - Wednesday, July 26, 2006 - link

    Sorry, looks like you misunderstood me, I was wondering about the AM2 platform bandwidth results @2.8Ghz and DDR2-800(page3). The Core2 scores are the same as "usual" ;-)

    So can you also say which bios you were using for the Asus M2N32-SLI ?

    thanks a lot

    Kiijibari
    Reply
  • Gary Key - Thursday, July 27, 2006 - link

    quote:

    So can you also say which bios you were using for the Asus M2N32-SLI ?


    0603 - 6/29/06
    Reply
  • OcHungry - Wednesday, July 26, 2006 - link

    But I dont understand why you need DDR2 800 or 1000?
    DDR2 667 w/ tighter timings can run @ 333 1:1 ratio (333x9 for FX62).
    Tell me what I am missing here?
    Reply
  • zsdersw - Thursday, July 27, 2006 - link

    quote:

    I dont understand


    Understatement of the year.

    Reply
  • zsdersw - Wednesday, July 26, 2006 - link

    quote:

    Intel would be best adwised to stop making CPUs and become an AMD chipset company ;-)


    Interesting notion. If it ever came to be, you can kiss price cuts (and innovation) on AMD chips goodbye.
    Reply
  • Shizen - Tuesday, July 25, 2006 - link

    Intel Core 2 comes out and AMD slashes prices across the board... the months ahead look like a great time to buy a new rig! Finally, I can retire my aging 2.8GHz Northwood and move on to PCI-E and DDR2. *_*

    Many thanks to the AnandTech dudes for keeping us abreast with the CPU wars, and I personally hope you guys come out with more articles geared for the midranged ($1000-$1500) buyer.

    Yeah, I like the idea of being a PERFORMANCE fanboi rather than a brand-centric one. o_o
    Reply

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