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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  • Calin - Tuesday, July 25, 2006 - link

    I hate to rain on your parade, but the E6x00 and X6800 (Extreme) desktop CPU won't see a dual socket mainboard - for that you must use Xeons.
    As for multisocket, it was a niche market when multicore was not available, it is (maybe even more so) when multicore is available. Quad core will reduce it even more for desktop use. As for Intel knowing multicore is the future, I think their quad core will be on market before AMD's quad core - and if you are worrying about performance, keep worrying - we can small talk about this and that all day long.

    AMD is in a much weaker position now - they must sell processors at half (or less) the profit they sold them until now, and the future is grim if you regard their profits. They could survive a long way, but they again are the budget CPUs, the best choice for small money.

    As for 64-bit, you are certainly right - just that right now, 64-bit is of little use on desktop, the operating systems suffer from drivers problems, 64-bit applications are few and far between. You might need 64-bit and profit from it, but you are a minority now.
  • Ingas - Tuesday, July 25, 2006 - link

    Maybe AMD in trouble.
    But not because of Core 2 Duo, but because of Woodcrest.

    AMD alwais said that only server processors giving profit.

    So ...
    With Dell's AMD Now - maybe it's not trouble for AMD at all.
  • Calin - Wednesday, July 26, 2006 - link

    Dell will only build enough AMD gear as not to lose business with their customers that WANT AMD gear. Even with higher performance losses on 4 sockets, Xeons Core2Duo (which are faster to boot) might put a fair fight against AMD - and then customers will choose based on other things than performance.
    I agree AMD Opteron scale better - but they start scaling from a lower performance
  • duploxxx - Wednesday, July 26, 2006 - link

    do you really think you're sure about that. compare the same speed of opteron vs woodcrest and you will talk different.. i know how it performs because i have a wood es system on my table. and i am not a big fan of hexus reviews but look at the site, the wood isn't so bright and shining knowing again it is a compare of 3.0 vs 2.6.
  • mesyn191 - Tuesday, July 25, 2006 - link

    For 2S systems Intel will have the lead til' K8L becomes available, but for 4S AMD will have Intel beat and that lead will only increase when K8L becomes available. They're definitly gonna be hurting profit wise, but they'll be doing better than they were when it was P4C vs. AXP and they got through that so I see no reason to worry about them going into bankruptcy before K8L comes out in volume.
  • sld - Tuesday, July 25, 2006 - link

    What is wrong with a desktop user looking at the performance of a desktop cpu?

    When you can get a 4x4 at the same price/performance ratio curve as a Core 2 Duo, do please inform me.

    I still believe AMD vs Intel is a David vs Goliath, although like the real David, AMD is beginning to get complacent with just a taste of power, and Core 2 is just what it needs to wake up and start dropping prices. :)
  • sld - Tuesday, July 25, 2006 - link

    I forgot to mention that Core 2 is worth a consideration over the K8, but if we really want to punish Intel for being the monster they are, we should institute a complete boycott over the purchase of their existing Netburst inventory. That should hurt them quite a bit...

    Picture a scenario where new chips go straight out of the warehouse and into the embracing arm of a bulldozer. When it comes to that point do you think they will resort to giving the cpus away?
  • mattsaccount - Tuesday, July 25, 2006 - link

    Are the Super Pi scores on page 7 right? The text says Conroe wins everything, but the Super Pi bench is reversed (I'm guessing the colors are just backward)
  • Wesley Fink - Tuesday, July 25, 2006 - link

    Since the lower score is better on Super Pi (faster time) the scales are reversed - from zero at the top to 90 at the bottom. The colors and values are correct, just upside down so the lowest score (fastest) is on the top like the other charts. You apparently caught that while I was typing this explanation :)
  • highlandsun - Tuesday, July 25, 2006 - link

    Have you got 32M digit results for Super Pi? Curious to see if that will exceed Conroe's cache and therefore reflect the real memory bandwidth. Also, results for running two copies of Super Pi at once on each system.

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