Synthetic: SiSoft Sandra, AIDA32 and Cachemem
On Sandra, the FX55 is a noticeable jump faster than the FX53 on the CPU test while the memory scores are just about even across the AMD board. THe Intel processors fall behind on the ALU (integer) CPU tests, but the HyperThreading features pushes them ahead of the AMD processors in FPU (floating point) calculations. In a single thread mode, however, keep in mind the Athlon 64 is indeed faster than the Intel 560 and EE processors.
The AIDA32 memory scores remain constant across the AMD board while the Prescott core Intel processors are quite a bit faster on this test than the Extreme Edition counterparts.
All the processors show similar performance in the Cachemem benchmark with the exception of the Intel EE. Keep in mind that the synthetic benchmarks are not always representative of real world performance.