The main thing we have discovered in our today's tests is that DDR3-2000 SDRAM is indeed possible on Socket AM3 systems. We now know the prerequisites for that: 1) any Phenom II X6 processor, 2) any of the many mainboards based on AMD’s 800 series chipsets, and 3) specially optimized memory modules.
As you can see, the most difficult requirement is to get such optimized memory. We were lucky to have a dual-channel 4GB kit from G.Skill (F3-16000CL7D-4GBFLS) which proved to be capable of working as DDR3-2000 on our Socket AM3 testbed. This memory kit is not without downsides, of course. For example, the modules are rather large because of the cooling elements, but we don't want to find fault with them as there are almost no alternatives available on the market. If you want high-speed DDR3 for your overclocked Phenom II X6-based computer, we do recommend you this memory kit from G.Skill.
Well, you shouldn’t be disappointed if you don’t find DDR3-2000 modules compatible with the Phenom II X6 as the performance benefits of such memory over DDR3-1600 only amount to 1-2% while memory kits like the G.Skill F3-16000CL7D-4GBFLS are some 50% more expensive. So, we are prone to regard the use of DDR3-2000 modules in an overclocked Socket AM3 system as a luxury rather than a necessity.
Although the optimized modules have no problems working with Phenom II X6 processors as DDR3-2000, there are obvious problems with AMD's memory controller in general. The highest memory frequency this controller permits is much lower than what you can get with Intel processors.
Hopefully, AMD will revise its memory controller so that the company’s upcoming Bulldozer and other architectures will work with high-speed memory without any limitations and reservations, especially as JEDEC-approved speeds of DDR3 SDRAM modules may go as high as 2000 and more megahertz in the very near future.