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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  • Coogcheese - Tuesday, July 25, 2006 - link

    Is the latency issue really due to intelligent look-ahead or the vast cache size difference between the two processors? I'd like to see a benchmark comparison between an 2MB cache opeteron and an equally cached/clocked/timed Conroe. That would settle some debate (yea, yea...wishful thinking).

    It could also help lend some insite to what AMD might do in the short & long term as a response as well.

    The author of the review seems to give alot of credit to "look-ahead" but I found this benchmark comparison to be interesting: http://www.hexus.net/content/item.php?item=6256&am...">http://www.hexus.net/content/item.php?item=6256&am...

    Opteron doesn't seem to have same problem that the Athlon does in terms of latency performance. Which could be why amd execs seem less than panicky at this point. It would allude to a market war similar to the megahurtz war that led to amd coming out with the model # system...this time it could be intel taking advantage of their capacity by laying the cache size smack down on amd instead of megahurtz.

    If it is cache size and not "look-ahead" then amd could (could mind you...but would they? and how many could they?) respond much quicker I'd think. If its new technology or a combo of cache and new tech then amd will be in a much worse position imho.

    Whatever the case its great for the consumer(me). Thank goodness for competition. Daddy needs a new pair of cores...and the price just got a whole lot better!

    Reply
  • ChronoReverse - Tuesday, July 25, 2006 - link

    It would indeed be very interesting to see a 2MB L2 1.6GHz Core 2 Duo E6200 compared against 2MB L2 1.6GHz Opteron 160.

    The shared L2 cache of the Conroe will give it a nice advantage though.
    Reply
  • bob661 - Tuesday, July 25, 2006 - link

    Anyonehave any speculation as to how much the initial Conroe's will cost? We pretty much know that the motherboards will be expensive but what about the CPU's? Reply
  • ChronoReverse - Tuesday, July 25, 2006 - link

    The pricing has been out for a while already. They're relatively reasonable considering the performance. Only the Extreme Edition as usual is really expensive (but still not as expensive as I'd have thought).


    Too bad the motherboards are so expensive. I'm taking a look at that Asrock board, but I doubt it'll have any good overclocking capability.
    Reply
  • Gary Key - Tuesday, July 25, 2006 - link

    quote:

    Too bad the motherboards are so expensive. I'm taking a look at that Asrock board, but I doubt it'll have any good overclocking capability.


    The less expensive boards for Conroe will fully hit the market near the end of August. ;-) We expect to see ECS, Foxconn, MSI, Epox, and others fully ramped up in a couple of weeks on the value boards. Until then, the Gigabyte DS3 is a really good board for overclocking the E6300/E6400 series and our Biostar and Abit boards continue to improve with each bios release. All three are under $145 now with others joining them shortly if the P965 is interesting to you. The ASRock board actually surprised us, but remember the VCore voltage cannot be adjusted. The $50~$100 market will be very interesting as the 945P, 946PL, and NV570SLI chipsets will dominate this section until the G965 boards start arriving in September if decent intergrated graphics are on your wish list, if not all of the boards will offer good performance for the money. The under $55 market will consist of VIA and SIS chipsets from PC-Chips and ASRock with a few majors like ECS and MSI having boards based on these chipsets.
    Reply
  • Wesley Fink - Tuesday, July 25, 2006 - link

    Everest Scores have been rerun with Version 3.01, which was released on July 16, 2006. Since the scores from the new version can not be compared to older Everest scores, we reran all the Everest benchmarks. 3.01 is said to provide full and complete support for Conroe and Merom. Values are different in that Memory WRITE and READ scores are reported as much higher than past Everest testing. Latency is also reported as closer between AM2 and Core 2 Duo with the 3.01 version of Everest. Charts and commentary have been revised using the new results. Reply
  • jjunos - Tuesday, July 25, 2006 - link

    Thanks for the update wes! It always shows the quality of the website when they listen to their community and and willing to rerun all their tests in the sake of being correct! kudos! Reply
  • TonyB - Tuesday, July 25, 2006 - link

    is it just me or did AMD just get pwned? Reply
  • bob661 - Tuesday, July 25, 2006 - link

    quote:

    is it just me or did AMD just get pwned?
    I personally don't care about who owns who. I just want competition so I can get this stuff for cheap. I'm a best bang for the buck guy.
    Reply
  • goinginstyle - Tuesday, July 25, 2006 - link

    Everyone benefits here with the performance improvements Intel has brought to the table and an AM2 3800+ at $150 is just an incredible value. Conroe made it easy for AMD users to upgrade their performance for very little money. Reply

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