Memory Test Configuration

When the article on AM2 processor performance was published a few days ago, the highest performance that could be reached with stability was DDR2-800 at 4-5-4 timings. A new BIOS will now allow the OCZ PC2-8000 reviewed in OCZ EL PC2-8000 XTC: Low Latency PLUS DDR2-1100 to run at 3-3-3 timings in AM2 prototype motherboards. This matches the highest performance achieved with this memory at DDR2-800 on the Intel 975x platform and allows a better comparison to fast DDR-400 memory on the AMD Socket 939 platform.

Pictures of the motherboards used for testing and/or photos of the AM2 processors tested might compromise our product sources, so there will be no pictures with this article. We can tell you that we now have several AM2 motherboards of very recent chipset updates along with several earlier boards that perform at a lower level. We are also testing our 4th spin of AM2, released days ago, and we have also seen increased performance with each spin of the AM2 CPU.

The design of the test bed is to assure, as much as possible, that the only difference between 939 and AM2 test systems is in the memory subsystems. This includes using the latest FX-60 X2 processor with the most recent DDR memory controller adjusted to the same speed as the AM2 X2 processor. Both motherboards are also based on similar NVIDIA chipsets, and all testing was done with the same Hitachi 200GB hard drive using the same OS installation. The MSI 7800GTX video card was used for testing in both systems. We also had NVIDIA 7900GTX and ATI X1900XT video cards available for testing, but we used the 7800GTX for easier comparison to results from other recent motherboard and memory reviews.

System Configuration
Processor: AMD AM2 X2
AMD FX-60 (X2) adjusted to match AM2 processor speed
RAM: OCZ EL PC2-8000 XTC (DDR2-1000, 2x1GB)
Crucial CLIII5N.32 PN56278 (DDR-500, 2x1GB)
Hard Drives: Hitachi 200GB SATA2
Video Card: MSI 7800GTX 256MB
Video Drivers: NVIDIA ForceWare 84.21
Power Supply: OCZ PowerStream 520W
Operating System: Windows XP Professional SP2
Motherboard: Pre-Release AM2 motherboard based on NVIDIA chipset
Asus A8N32-SLI Deluxe


While the speeds of top DDR and DDR2 are different, we tried to match other factors within memory as much possible. Both DDR and DDR2 were 2 GB kits consisting of 2x1GB dimms. DDR was top-line DDR500 tested at the fastest DDR400 2-2-2 timings; DDR2 was top-line DDR2-1000 tested at the fastest DDR2-800 3-3-3 timings. DDR memory that performs at DDR400 2-2-2 is a premium part and it was compared to a premium DDR2 part.

A more mainstream comparison would have been DDR400 3-3-3 to a DDR2-667 4-4-4 pushed to DDR2-800. The performance differences in the mainstream parts would have been similar, but they would not really reflect the state of the memory market in about 6 weeks. We know that all the top memory vendors plan new DDR2-800 high performance and mainstream parts for the AM2 launch, and offerings at the top of mainstream and high-end will be different in a few weeks. The OCZ PC2-8000 we used for testing, however, is a just-launched DDR2 memory based on what is widely expected to be the best performing DDR2 memory chips available for the near future. This top to top comparison should therefore provide a clear approximation of real performance when AM2 launches.

There is always room for some unexpected AMD announcements, but as Anand explained in his article about the April spin of AM2: ". . . according to internal AMD documents, AM2 CPUs are going to start being sold to distributors starting next month, leaving very little time for significant changes to the CPU to impact performance. We feel that now is as good of a time to preview AM2 performance and put things into perspective as we're likely to get before the official launch." We all can hope for a surprise from AMD, but with distributors receiving parts in less than a month and with official launch just 6 weeks away, we are probably testing what is very close (if not identical) to the final AM2 part.

Index Socket 939 Fast DDR-400 vs. AM2 Fast DDR-2
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  • Ecmaster76 - Saturday, April 15, 2006 - link

    Wouldn't it be the best way to suck up bandwidth? We already knew a single core had enough bandwidth from the 754-939 transition.

    I guess its not that big a deal now because the parts aren't even for sale. But as long as you do tsome multitasking articles on the final hardware I'll be happy.
    Reply
  • IntelUser2000 - Saturday, April 15, 2006 - link

    So... the conclusion is that DDR2-800 is needed to outperform DDR400. DDR2-667 is slower than DDR400. The Inquirer is correct, contrary to some other opinions. Reply
  • Wesley Fink - Saturday, April 15, 2006 - link

    Latency and Bandwidth of DDR2-533 are about the same as DDR400, and DDR2-667 and DDR2-800 are both faster. Games and Applications SHOULD be faster on both DDR2-667 and DDR2-800. However, given current aopplications and the AM2 memory controller, the applications and games are about the same at DDR2-667 - and DDR2-800 is faster as you state.

    This is likely the result of the late pre-release AM2 memory controller and applications/games themselves not being optimized for DDR2 on AM2. Both will likely be fixed very quickly, and actual performance of DDR2-533 should then be roughly on par with DDR400 - with 667 and 800 both faster.
    Reply
  • psychobriggsy - Saturday, April 15, 2006 - link

    If 2.5GHz was a 40% overclock, then the AM2 processor tested must have been running at 1.8GHz (9x200, i.e., it was also unlocked for you to get 10x250).

    It's not surprising that a 1.8GHz K8 processor wouldn't benefit from DDR2 much - indeed I expect that most of the application improvements were just from the slightly reduced latency at DDR2-800 rather than actually having more bandwidth available.

    I wonder what a stock 2.8GHz AM2 X2 with DDR2-800 would get against a stock 2.8GHz 939 X2 with DDR-400? No, I don't think it will be a miracle, but just possibly it will start actually needing the extra bandwidth available, which could lead to a greater gap between the two platforms.

    I guess we'll find out in under 2 months.
    Reply
  • Wesley Fink - Saturday, April 15, 2006 - link

    The AM2 processor was NOT a 1.8GHz x2. I stated the CPU could overclock 40% at stock speeds, but the 10x250 is not that 40% overclcok. We chose that ratio because it is a clock speed our DDR2 memory could handle and it was also a speed doable on 939 for a reasonable comparison. We actually had two AM2 processors this round, a top-line AM2 and a more mainstream processor. We looked at performance from both, and it was the same at the same processor speed. The DDR2 memory controller reports as Rev. F.

    As for the question about manufacture date, we are providing as little information about these pre-release processors and motherboards as possible to protect our sources. We have several sources who work with us to bring you the latest news before anyone else, and we don't want to compromise those relationships. Therefore we are not providing any information that might make it easier for AMD and others to trace our sources.

    We can assure you these are the latest Rev. AM2 shipped to AMD partners in early April as we have evaluated 4 versions since mid-January. This is also the first rev. to fully support DDR2-800.
    Reply
  • Viditor - Saturday, April 15, 2006 - link

    quote:

    we are providing as little information about these pre-release processors and motherboards as possible to protect our sources

    Fair enough...had to ask.
    Reply
  • Viditor - Saturday, April 15, 2006 - link

    My concern is that while Anand is just receiving the part, if it's off of a recent production run then AMD will have some problems with the launch. Usually you need a full turn's worth of product in inventory for a launch...if they are just turning out final product now, then my guess is there will be shortages come July. Of course since they have doubled their capacity recently it will be much less, but still...it doesn't bode well.

    Anand, could you confirm the manufacture date of the chip you tested for us please?
    Reply
  • Viditor - Saturday, April 15, 2006 - link

    Apologies...I should have addressed the previous question to Wesley (sorry mate).
    I know that APM allows AMD to change anything (even down to individual dice on the wafer) at any point in the process, but my concern is inventory levels here. If you could please confirm the production date on the chip you used for testing, it would help me significantly with my analysis of the upcoming launch.

    Cheers!
    Reply
  • Jynx980 - Saturday, April 15, 2006 - link

    Typo on page 3, paragraph 5:
    quote:

    we DDR timings we have tested
    Reply
  • Wesley Fink - Saturday, April 15, 2006 - link

    The extra "we" has been removed. Reply

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