As I've already posted in Hardware news room
'The real reason that Bulldozer did not stack up in the benchmarks is the compiler used for for each of the benchmarks. All of these closed-source benchmarks are compiled on the standard Intel compiler with the Intel libraries. It is not optimized to support any instructions beyond SSE3 for any processor other than Intel chips. SSE4.1, SSE4.2, AVX, and FMA4 significantly increase the floating point performance of AMD processors, but are not used by code compiled on an Intel compiler.
If you look at the integer performance of the benchmarks, AMD almost always out-performs the intel chips and shows a 15-30% increase in performance over the Phenom II x6 processors. If the compiler used was completely optimized for both Intel and AMD, floating point performance would also show similar gains.
Lastly, under full load where all of the threads are being used, the Intel chip is not physically capable of beating the AMD chip. 4 cores that complete one instruction each per cycle cannot physically beat 8 cores completing 1 instruction each per cycle, when threads are continually running.'