like AMD has done its homework with the Barcelona, as we continue to read the AMD documentiation we found here
, it is pretty clear that AMD is looking towards the future. With DDR2-1066 and DDR3 support for 1,066, 1,333 and 1,600MHz memory modules, there should be no worries about using slow memory with the Barcelona core.
There does seem to be some limitations though, although we're not quite clear on the information as different parts of the documentation mentions different things, but you might only be able to run two DIMM's when you use DDR2-1066 or DDR3-1066. Why this is, we're not sure.
AMD has also added support for up to 8GB per DIMM, although as the documentation caters for both the Phenom and the Opteron processors, some of the information isn't clear in terms of which CPU it talks about. Some limitations might be imposed on the consumer level products, just as Intel has done in the past with its consumer level chipsets.
We presume that the Phenom processors won't be able to use three or four DIMM's per channel, although this is mentioned in the documentiation. AMD also supports spares, which is handy for fault tolerent servers, but it's a costly option to have extra memory on your server that's not being used.