Intel Xeon 5600 (Westmere-EP 6 cores-12threads) processors review
 

For multithreaded workloads that aren't gated primarily by I/O throughput, the addition of two cores at the same clock frequencies and power envelopes—along with a proportional increase in cache—is a clear performance win. Even workloads that rely on streaming quite a bit of data from memory, as our two HPC-oriented benchmarks do, may benefit from the move to Westmere thanks to its larger cache and aggressive data pre-fetching algorithms. That speaks to the scalability of this still relatively new system architecture, among other things.

http://techreport.com/articles.x/19196