AnandTech IT has a quick review of the upcoming six-core, 32nm Intel Xeon 56xx processor, which includes several different database benchmarks. Their conclusion is that this CPU is a significant improvement over the very impressive Intel Xeon 55xx processor, and that it simply dominates anything that AMD currently has available.
Part of me hates to see that, because I think everyone is better off if AMD is a viable competitor to Intel in the server space. Right now, AMD is not very competitive (performance-wise) with Intel’s current and rapidly upcoming offerings. Perhaps this will change when the new AMD Bulldozer-based multi-threaded processors appear in 2011.
These new Xeon 5600 processors have six cores, plus hyper-threading, so you get 12 logical processor cores per physical CPU. The shared L3 cache grows from 8MB to 12MB. L3 cache size is very important for database performance. The memory controller is also improved, so you can add more memory sticks without decreasing memory bandwidth as much as with the Xeon 5500 series. The 5600 series is also socket compatible with the 5500 series, so existing two socket server designs will be able to use them with a BIOS update. This means that systems with this processor should be available very soon. ZDNet has some more details here.
Glenn Berry's SQL Server Performance 