You already know that the AM2 does modestly outperform Athlon64 Socket 939. This article explores how the memory controllers compare in latency and bandwidth, memory performance at various DDR2 settings compared to fast DDR400 2-2-2 memory, and basic overclocking performance of AM2 compared to Socket 939 when the CPU and memory are both pushed to improve performance. Here's an excerpt:

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.