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.
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.
The introduction of AM2 merely increased the AMD latency advantage. AM2 latency was slightly lower than DDR latency on AMD.
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.
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sld - Tuesday, July 25, 2006 - link
Yes I second the importance of a 32M run, because I want to know how Core 2 Duo does when the dataset does not fit into the L2 cache. The Intel fanboys at xtremesystems are annoying me with their whoops of glee over the 1M and 2M results.The performance difference in games and superpi is large enough to be termed anomalous, simply because superpi is a feel-happy benchmark.
Calin - Tuesday, July 25, 2006 - link
I've had the same issue on understanding the graphic - but I think it is much better now (top representing better performance, with the scale inverted)Anyway, great article!
As for the increases in cache helping AMD processors, I guess not - considering the small difference from 512k to 1M.
mattsaccount - Tuesday, July 25, 2006 - link
Never mind, I'm tired :)goinginstyle - Tuesday, July 25, 2006 - link
Page 7 is going to upset a lot of AMD fans.Page 9 index description needs to be "conclusion".
Great article and would love to see this comparison with the E6600 and E6300 CPUs against the competing AMD cpus. A lot of us will be buying these two processors and probably plain DDR2800.
OcHungry - Tuesday, July 25, 2006 - link
Can I ask you what memory timings you used?Since you have stated that memory speed does not affect conroe, would it be fair to assess that you used tightest timings for AM2?
If not: why?
About what page is going to make AMD users upset or hate the page, I totally disagree with you. You actually brought some lights to the whole scheme of things, unintentionally and unknowingly. You have helped to prove that Conroe will only be a mere 1 or 2% faster than AM2, which is not noticeable in real life situation. Conroe is only faster in Spi- But again, AMD beats Intel in memory bandwidth by a great margin. Memory bandwidth is much more important than SPI in terms of game and general cpu task(s). I will prove to everyone, that AMD is just as fast as conroe and post my reasoning in the cpu section, as soon as I have analyzed your benchmark data and made my calculations. But I need to know what memory timings you did use thu. A screenshot of timings would be great.
Again, thank you for this review that helped us open our eyes and see things in a better perspective.
Gary Key - Tuesday, July 25, 2006 - link
Wes replied earlier in the comments section but the settings are now posted on page 4 of the review.
goinginstyle - Tuesday, July 25, 2006 - link
Caluclations? I would like to see your benchmarks on actual hardware and not some scribbling on your Happy Meal napkin. I can caluclate that you are an idiot but really do not have the time to do it since I have a real life.
zsdersw - Tuesday, July 25, 2006 - link
1 or 2% faster? Please share with the rest of us what you're smoking.
Conroe is significantly faster on almost all fronts... in spite of having lower memory bandwidth.
Calin - Wednesday, July 26, 2006 - link
I suggest you to use a tractor and two trailers - one for persons and one for cargo. Even if you won't go faster than people with cars, you will have a huge bandwidth (persons and cargo bandwidth).If you buy your processor for bandwidth, choose whatever you want. If you buy it for speed, buy based on actual performance
bob661 - Tuesday, July 25, 2006 - link
I thought you didn't care about this stuff?