AnandTech: First Look: AM2 DDR2 vs. 939 DDR Performance

Final Words

When the article OCZ EL PC2-8000 XTC: Low Latency PLUS DDR2-1100 was posted a couple of weeks ago, the potential of this incredibly fast DDR2 memory on the upcoming AM2 platform was clear. What was not expected was that the opportunity to run the DDR2-1000 memory through its paces on an AM2 was only a couple of weeks away. After looking more closely at DDR2 memory performance on the 4th spin of the AM2 processor it is clear AMD will definitely be able to launch AM2 with the expectation of better performance than the Socket 939 it replaces. This avoids one of the huge pratfalls that plagued Intel in their move to DDR2.

However, the memory bandwidth increases of up to 30% on AM2 and the Latency improvements of 12 to 16% compared to the fastest DDR memory on socket 939 do not yield much in real-world performance. The real-world performance increase for AM2 compared to Socket 939 will likely be very small - in the range of no increase to about 7%, depending on the application.

In normal times this would be great news! In times where previews of Intel's new Conroe architecture show solid 20%+ improvements in performance compared to AMD Socket 939, these smaller AM2 increases are reason for concern. It certainly appears that unless some unforeseen miracle happens, the move from Socket 939 DDR to AM2 DDR2 just can't generate anywhere near the performance improvement AMD really needs to combat Intel's Conroe. This article evaluated memory and gaming performance, but you can see comparisons of General Performance, multimedia and encoding in the companion article AMD Socket-AM2 Performance Preview.

Not all is gloom in the AMD camp, however, as there are certainly bright spots. AM2 IS faster than Socket 939, with even more possible DDR2 bandwidth for the future. Unfortunately, unless AMD makes revisions to the core and/or adds more cache with the 65nm die-shrink there is not much improvement from the move to AM2. The extra bandwidth and lower latency just don't translate into meaningful performance improvements with today's applications.

There are also a few general observations about using DDR2 with the new upcoming AM2. Using fast, top-line memory DDR2-533 is roughly equivalent in bandwidth to fast DDR400 memory. That observation should also hold with mainstream memory where DDR400 3-3-3 should perform about like DDR2-533 4-4-4. Most memory manufacturers will also be producing fast high-end DDR2-800 and more mainstream DDR2-667 and DDR2-800 parts for launch with AM2, so there will likely be many more memory choices when AM2 launches.

Last, the move to a unified memory specification with Intel will likely be a good development for those looking to buy new DDR2 memory. With AMD and Intel both using DDR2 there will likely be more innovation in the DDR2 market, more choices, and even better prices. Add to that the expectation that both AM2 and Conroe will launch with official DDR2-800 support and faster DDR2 memory should be much easier to find and afford in the near future.

It appears AMD will succeed in launching a faster on-processor DDR2 memory controller. The latest AM2 pre-release samples are showing significant improvements over Socket 939 DDR in both memory bandwidth and latency. Unfortunately, the current AMD architecture running current applications and games doesn't appear to need the additional bandwidth or reduced latency. This may change in the future, but for now the move to AM2 and DDR2 memory looks like it will yield far too little in performance improvements to keep AMD competitive in the upcoming desktop marketplace.

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